S5 Geography Notes PDF

Table of Contents UNIT 1: STATISTICAL GRAPHS, DIAGRAMS, AND MAPS............................................................. 1 1.1. Definition of statistics and importance of statistical graphs and diagrams in Geography.............................................................................................................................................................. 1 1.1.1. Definition of Statistics....................................................................................................................... 1 1.1.2. Importance of statistical graphs and diagrams in geography........................................... 1 1.2. Line and curve graphs.............................................................................................................................. 2 1.2.1. Simple line and curve graphs......................................................................................................... 2 1.2.2. Group or comparative graphs....................................................................................................... 4 1.2.3. Compound line graph....................................................................................................................... 6 1.2.4. Divergence line graphs..................................................................................................................... 8 1.3. Bar Graphs................................................................................................................................................... 10 1.3.1. Simple bar graphs.................................................................................................................................... 11 1.3.2. Group bar graph................................................................................................................................ 13 1.3.3. Compound bar graph...................................................................................................................... 14 1.3.4. Divergence bar graphs.......................................................................................................................... 15 1.3.5. Age and sex graphs.......................................................................................................................... 17 1.4. Simple divided circles............................................................................................................................. 20 UNIT 2: BEARINGS, DIRECTIONS, DISTANCES AND AREAS ON A MAP............................ 23 2.1. Location of places using the grid reference.................................................................................... 23 2.1.1. The four-figure grid reference..................................................................................................... 23 2.1.2.1. The six-figure grid reference............................................................................................ 24 2.2. Stating directions and bearings on topographic maps.............................................................. 25 2.2.1. Direction....................................................................................................................................................... 25 2.2.2. Bearing................................................................................................................................................... 25 2.3. Measure the distance on the maps: straight line and curved line.................................... 26 2.3.1. Straight line distance.............................................................................................................................. 27 2.3.2. Curved Distances....................................................................................................................... 27 2.4. Calculate the areas on topographic maps: regular and irregular shape............................. 27 2.4.1. Calculate areas of regular shapes............................................................................................... 28 2.4.2. Calculate areas of irregular shapes............................................................................................ 28 2.5. Representation of relief on the map.................................................................................................. 29 2.5.1. Altitude................................................................................................................................................. 29 2.5.2. Contours............................................................................................................................................... 30 i Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 UNIT 3: MAP WORK INTERPRETATION.....................................................................................................31 3.1. Interpretation of physical aspects from maps/photographs.................................................31 3.1.1. Interpretation of geological features.................................................................................31 3.1.2. Interpretation of slopes from a map/photograph.......................................................32 3.2. Interpretation of drainage and landforms from a map/photograph............................33 3.2.1. Interpretation of drainage features from a map/photograph................................33 3.2.2. Interpretation of landforms..................................................................................................33 3.3. Relationship between physical and human aspects on maps/photographs....................35 3.3.1. Drainage patterns..................................................................................................................................... 35 3.3.2. Settlement patterns................................................................................................................................. 37 3.3.3. Vegetation.................................................................................................................................................... 38 3.3.1. Communication networks..................................................................................................................... 39 UNIT 4: THE UNIVERSE AND THE SOLAR SYSTEM....................................................................... 40 4.1. The universe........................................................................................................................................................ 40 4.1.1. Definition of the universe and Components of the universe..........................................40 4.1.2. The components of the universe................................................................................................40 4.2. Solar system: sun and planets.............................................................................................................41 4.2.1. Characteristics of the Sun.......................................................................................................41 4.2.2. The influence of the sun on the Earth...............................................................................42 4.2.3. Characteristics of different planets and their positions............................................42 4.3. Earth: Peculiar elements of the earth................................................................................................. 45 4.4. Earth’s movements............................................................................................................ 45 4.4.1. Rotation of the Earth............................................................................................................................... 45 4.4.2. Revolution of the Earth...........................................................................................................46 4.5. Phases of the moon............................................................................................................................48 4.6. Influence of the moon on the earth.............................................................................................49 Eclipses of the moon...................................................................................................................................49 Tides........................................................................................................................................................................... 50 UNIT 5: THE ORIGIN OF THE EARTH.................................................................................................. 50 5.1. Theories of the origin of the earth............................................................................................................. 50 5.1.1. The Biblical or creation theory........................................................................................................... 51 5.1.2. Big Bang Theory................................................................................................................................51 5.2. Characteristics of the Earth.......................................................................................................................... 52 5.2.1. The shape of the earth is spherical................................................................................................... 52 ii Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 5.2.2. The shape of the earth is oblate......................................................................................................... 53 5.2.3. The Earth’s size: radius, diameter, circumference, volume, and mass.......................54 5.2.4. The Earth’s gravity...................................................................................................... 54 The influence of the gravity.....................................................................................................................54 5.3 : The internal structure of the Earth and mineral composition...............................................55 5.3.1. The internal structure of the earth................................................................................................... 55 5.3.2. The mineral composition of the Earth............................................................................................. 56 5.4. Superficial configuration of the earth: Continents and Oceans.............................................57 5.4.1. Continents.................................................................................................................................................... 58 5.4.2. Oceans........................................................................................................................................................... 58 5.5. Geological time scale.........................................................................................................................59 UNIT 6: INTERNAL LANDFORM PROCESSES................................................................................... 60 6.1. Faulting and processes leading to the formation of different faulted features...............60 6.1.1. Forces causing faulting...................................................................................................................60 6.1.2. Meaning of faulting and fault................................................................................................61 6.1.3. Main parts of a fault and the Processes of faulting......................................................61 6.1.4. Types of faults.............................................................................................................................62 6.1.5. Influence of faulting on landscape and drainage................................................................64 6.2. Definition of folding and its process...........................................................................................71 6.2.1. Meaning of folding and folds........................................................................................................71 6.2.2. Processes of folding..................................................................................................................72 6.2.3. Types of folds..............................................................................................................................72 6.2.4. Influence of folding on drainage and landscape...........................................................75 6.2.5. Impacts of folding on physical environment..................................................................76 6.3. Meaning, causes and types of warping......................................................................................77 6.3.1. Meaning of warping..................................................................................................................77 6.3.2. Types of warping.......................................................................................................................77 6.3.3. Causes of warping............................................................................................................................77 6.3.4. Landforms associated with warping........................................................................................77 6.3.5. Areas of Warping..............................................................................................................................78 6.3.6. Influence of warping on drainage..............................................................................................78 6.4. Processes of vulcanicity and volcanic materials....................................................................79 6.4.1. Introduction to Vulcanicity and Volcanicity...................................................................79 6.4.2. Materials of vulcanicity...........................................................................................................80 iii Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 6.4.3. Intrusive and extrusive features................................................................................................81 6.4.3. Types of volcanoes and their characteristics.................................................................84 6.4.4. Influence of volcanicity on drainage..................................................................................85 6.4.5. Impact of volcanicity to the human....................................................................................86 6.4.6. World distribution of volcanoes..........................................................................................87 6.5. Meaning of Earthquakes and its related concepts................................................................87 6.5.1. Introduction......................................................................................................................................... 87 6.5.2. Description of the terminologies associated with Earthquakes.............................88 6.5.3. Causes of earthquakes.............................................................................................................89 6.5.4. Consequences of earthquakes..............................................................................................90 6.5.5. Measures to curb earthquake effects........................................................................................ 90 UNIT 7: SOILS.........................................................................................................................................................90 7.1. Soil constituents................................................................................................................................................ 91 7.2. Morphological properties, profile and catena, fertility of the soil........................................92 7.2.1. Soil properties............................................................................................................................................ 92 7.2.2. Soil profile and catena....................................................................................................................96 7.2.3. Soil fertility..........................................................................................................................................98 Factors affecting soil fertility..................................................................................................................98 UNIT 8: WEATHER AND CLIMATE OF THE WORLD..................................................................... 99 8.1. Introduction........................................................................................................................................................ 99 8.2. Atmosphere......................................................................................................................................................... 99 8.2.1. Meaning of the atmosphere..........................................................................................................99 8.2.2. The structure of the atmosphere....................................................................................................... 99 Thermal characteristics of atmosphere....................................................................................................100 8.2.3. Composition of atmosphere...................................................................................................... 103 8.2.4. Importance of the atmosphere.........................................................................................................105 8.3. Elements of weather and climate................................................................................................... 106 The elements of weather and climate................................................................................................... 106 8.3.1. Temperature.............................................................................................................................................106 8.3.1.1. Factors influencing temperature variation..............................................................................106 8.3.1.2. Measurement and recording of temperature................................................................. 108 8.3.1.3. Terms related to temperature.......................................................................................................108 8.3.1.4. Impact of temperature on the environment................................................................... 109 8.3.2. Precipitation......................................................................................................................................110 iv Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 8.3.2.1. Forms of Precipitation..................................................................................................... 110 8.3.2.2. The water cycle...........................................................................................................................111 8.3.2.3. Types of rainfall.................................................................................................................. 112 8.3.2.4. Factors influencing rainfall formation...................................................................... 115 8.3.2.5. Measurement and recording of rainfall.................................................................... 115 8.3.2.6. Terms related to Rainfall................................................................................................ 116 8.3.3. Wind............................................................................................................................................. 117 8.3.3.1. Measurement and recoding of wind direction....................................................... 117 8.3.3.2. Measurement of wind speed......................................................................................... 117 8.3.3.3. Factors influencing the nature and movement of winds................................... 118 8.3.3.4. Types of winds.................................................................................................................... 118 8.3.3.5. Influence of winds on weather conditions and human activities................... 124 8.3.3.6. Air masses......................................................................................................................................125 8.3.3.7. Anticyclone:...................................................................................................................................129 8.3.4. Atmospheric humidity.......................................................................................................... 130 8.3.4.1. Measurement and recording of humidity................................................................ 130 8.3.4.2. Types of atmospheric humidity................................................................................... 130 8.3.4.3. Factors influencing atmospheric humidity............................................................. 131 8.3.4.4. The significance of humidity to the environment................................................. 132 8.3.5. Cloud cover................................................................................................................................ 132 8.3.5.1. Types of clouds and their characteristics................................................................ 132 8.3.5.2. Factors influencing the formation and the shape of clouds.............................. 134 8.3.5.3. Effects of clouds on weather......................................................................................... 134 8.3.6. Sunshine..............................................................................................................................................134 8.3.6.1. Measurement and recording of sunshine................................................................ 135 8.3.6.2. Factors influencing the amount of solar radiation............................................... 135 8.3.6.3. Influence of sunshine on the environment.............................................................. 136 8.3.7. Atmospheric pressure...................................................................................................................137 8.3.7.1. Measurement and recording of atmospheric pressure...................................... 137 8.3.7.2. Factors influencing the distribution of atmospheric pressure...............................137 8.3.7.3. Pressure types..............................................................................................................................138 8.3.7.4. Location of different world pressure belts and their characteristic.............. 138 8.3.7.5. Factors that influence world climate.................................................................................139 8.4. Types of climate and their characteristics............................................................................ 141 v Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 8.4.1. Tropical zones...................................................................................................................................141 8.4.1.1. Equatorial climate......................................................................................................................142 8.4.1.2. Tropical marine climate...........................................................................................................143 8.4.1.3. Tropical continental climate..................................................................................................144 8.4.1.4. Savanna climate (Tropical wet-and-dry climate)................................................. 144 8.4.1.5. Tropical desert climate............................................................................................................145 8.4.1.6. Tropical Monsoon Climate............................................................................................. 145 8.4.2. Temperate zone...............................................................................................................................146 8.4.2.1. Mediterranean Climate.................................................................................................... 147 8.4.2.2. Temperate Maritime Climate........................................................................................ 147 8.4.2.3. Continental temperate climate.............................................................................................148 8.4.3. Cold zone.................................................................................................................................... 148 8.4.3.1. Polar and Tundra climate............................................................................................... 149 8.4.3.2. Mountain climate............................................................................................................... 149 8.5. Influence of climate on human activities..................................................................... 150 UNIT 9: NATURAL VEGETATION OF THE WORLD..................................................................... 150 9.1. Tropical forests and their characteristics.......................................................................................151 9.1.1. Equatorial forests............................................................................................................................151 9.1.2. Tropical Monsoon forests............................................................................................................152 9.1.3. Mountain tropical forests.............................................................................................................153 9.2. Temperate forests and their characteristics.................................................................................154 9.2.1. Mediterranean forests...................................................................................................................155 9.2.2. Coniferous forests / Taiga Forest.................................................................................... 156 9.2.3. Deciduous forests................................................................................................................... 157 9.3. Grasslands in tropical zone and their characteristics....................................................... 157 9.3.1. Savannah humid...................................................................................................................... 158 9.3.2. Steppe/ Savannah dry.......................................................................................................... 158 9.4. Grasslands in temperate zone.................................................................................................... 159 The characteristics of temperate grasslands are:.................................................................................160 9.5. Desert Vegetation......................................................................................................................................160 9.5.1. Hot desert vegetation............................................................................................................ 161 9.5.2. Cold desert vegetation........................................................................................................ 163 9.5.3. Tundra vegetation.................................................................................................................. 163 9.6. Mountain vegetation....................................................................................................................... 164 vi Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 9.6.1. Tropical Mountain vegetation........................................................................................... 164 9.6.2. Temperate mountain vegetation..............................................................................................165 9.7. Aquatic, marsh and Swamp vegetation.................................................................................. 166 9.7.1. Mangrove vegetation............................................................................................................. 166 9.7.2. Aquatic plants.......................................................................................................................... 167 9.8. The factors which influence natural vegetation.................................................................. 168 9.9. The importance of natural vegetation..................................................................................... 169 UNIT 10: POPULATION GROWTH IN THE WORLD..................................................................... 170 10.1. Introduction to Population...............................................................................................................170 10.2. World Population distribution.............................................................................................. 173 Table 1: Top ten most populated countries in the world (2018)..................................................173 10.2.1. Population Density................................................................................................................. 173 10.2.1.1. The densely populated areas:...............................................................................................173 10.2.1.2. The moderately populated areas.........................................................................................174 10.2.1.3. The sparsely populated areas:..............................................................................................174 10.2.2. Factors responsible for the distribution of population in World............................ 174 10.3. Population concepts and its related effects...................................................................... 176 10.3.1. Optimum population............................................................................................................. 176 10.3.2. Under population.................................................................................................................... 177 10.3.3. Overpopulation........................................................................................................................ 178 10.4. Population problems of developed and developing countries................................. 179 10.4.1. Population problems of developed countries and their solutions..................... 179 10.4.2. Population problems of developing countries and their solutions.................... 180 10.5. Population growth...................................................................................................................... 182 10.5.1. Factors influencing birth rate....................................................................................................182 10.5.2. Factors influencing death rate...................................................................................................183 10.5.3. Factors influencing the rapid population growth..................................................... 183 10.5.4. Effects associated with rapid population growth..................................................... 184 10.5.5. Ways of controlling population growth........................................................................ 185 10.6. Population structure and the composition....................................................................... 186 10.6.1. Population Pyramid............................................................................................................... 186 10.6.2. Sex composition...................................................................................................................... 186 10.6.3. Population age composition............................................................................................... 187 10.6.4. Active and inactive population......................................................................................... 188 vii Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 10.6.5. Standard of living.................................................................................................................... 188 10.6.6. Education............................................................................................................................................188 10.7. Population Policies in the World........................................................................................... 189 10.7.1. Population policies in developed country.................................................................... 189 10.7.2. Population policies in developing countries................................................................ 189 10.7.3. Effects of population policies on population growth............................................... 190 10.7.4. Impacts of early sex and possible prevention measures......................................... 190 10.7.4.1. Causes of early sex............................................................................................................. 190 10.7.4.2. Negative effects of early sex on the livelihood of the teens............................... 191 10.7.4.3. Possible solutions to prevent early sex and related consequences....................191 10.7.5. The impact HIV/Aids on social economy development of country and possible prevention measures............................................................................................................................... 192 10.7.6. The impact of STDs and possible prevention measures.......................................... 193 10.8. Migration........................................................................................................................................ 194 10.8.1. Types of migrations............................................................................................................... 194 10.8.2. Causes of migrations............................................................................................................. 195 10.8.3. The effects of migrations in the world............................................................................ 196 10.8.4. The measures to be taken to control migration...............................................................198 UNIT 11: URBANIZATION IN THE WORLD................................................................................... 198 11.1. Rural settlement...........................................................................................................................................199 11.1.1. Types of rural settlement.................................................................................................................199 11.1.2. Factors influencing rural settlement..........................................................................................200 11.1.3. Effects of rural settlements.............................................................................................................200 11.1.4. Solutions to the problems affecting rural settlement.........................................................201 11.2. Urbanization in the world................................................................................................................ 201 11.2.1. Definition of basic terms........................................................................................................... 202 11.2.2. Location of major world urban centers and ports.......................................................... 203 11.2.3. Factors influencing urban development in the world.................................................. 203 11.2.5. Impact of world urbanization on the environment....................................................... 204 UNIT 12: AGRICULTURE IN THE WORLD....................................................................................... 204 12.1. Types of crop Cultivation................................................................................................................. 204 12.1.1. Subsistence farming................................................................................................................... 205 12.1.2. Cooperative farming.................................................................................................................. 210 12.1.3. Plantation farming...................................................................................................................... 212 viii Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 12.1.4. Market gardening........................................................................................................................ 214 12.1.5. Horticulture............................................................................................................................................215 12.1.6. Truck farming............................................................................................................................... 216 12.1.7. Collective agriculture................................................................................................................. 217 12.1.8. Commune farming...................................................................................................................... 218 12.2. Factors for increasing the agricultural production and problems affecting the agriculture in the developing countries................................................................................................ 220 12.2.1. Factors for increasing the agricultural production.............................................................220 12.2.2. Problems affecting the agriculture in the developing countries............................... 221 Case studies of crop growing in selected countries......................................................................... 222 Sugarcane in South Africa...................................................................................................................... 222 Cotton growing in Sudan....................................................................................................................... 225 12.3. Livestock farming................................................................................................................................ 227 12.3.1. Pastoralism.............................................................................................................................................227 12.4.2. Factory farming....................................................................................................................................230 12.3.3. Ranching and dairy farming................................................................................................... 232 12.3.4. Dairy farming................................................................................................................................ 233 12.4. Factors and problems affecting the livestock farming and ways of improving the livestock farming........................................................................................................................................... 234 12.4.1. Factors affecting livestock farming...................................................................................... 234 12.4.2. Problems facing livestock farming....................................................................................... 235 12.5.3. Ways to improve livestock farming..................................................................................... 236 Case studies of livestock farming in selected countries................................................................. 237 Ranching in Botswana............................................................................................................................. 237 Dairy farming in Holland....................................................................................................................... 238 Sheep rearing in Australia..................................................................................................................... 239 UNIT 13: FORESTRY IN THE WORLD...................................................................................................... 239 13.1 : Importance of forest exploitation forests and problems affecting lumbering............. 240 13.1.1. Importance of forest exploitation forests........................................................................... 240 13.1.2. Problems limiting forest exploitation.................................................................................. 241 13.2 : Methods of forest exploitation/lumbering and forest conservation measures.......... 243 13.2.1 : Methods of forest exploitation............................................................................................... 243 13.2.2 : Forest conservation measures.......................................................................................................244 Forestry studies in selected countries...........................................................................................................245 ix Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 Forestry in Gabon...................................................................................................................................... 245 Forestry in British Columbia..................................................................................................................... 247 UNIT 14: FISHING IN THE WORLD.................................................................................................... 250 14.1. Methods used in Fishing and Types of fish and fishing in the world............................. 250 14.1.1. Traditional fishing methods.................................................................................................... 250 14.2.2 : The modern fishing methods.................................................................................................. 253 14.2.3 : Types of fishes and fishing...................................................................................................... 255 14.3. Factors influencing development of fishing..................................................................... 256 14.3.1. Physical factors influencing the development of fishing........................................ 256 14.3.2. Human factors influencing the development of fishing.......................................... 258 14.4. Importance of fish and fishing............................................................................................... 260 14.5. Problems affecting marine fisheries and Solutions........................................................ 262 14.5.1. Problems affecting inland fisheries of the world....................................................... 262 14.5.2. Future prospects of inland fisheries................................................................................ 264 14.6. Fish conservation and preservation..................................................................................... 265 14.6.1. Fish conservation............................................................................................................................265 14.6.2. Fish conservation............................................................................................................................267 UNIT 15: MINING IN THE WORLD..................................................................................................... 268 15.1. Methods of mining.............................................................................................................................. 272 15.1.1. Opencast or open pit mining.................................................................................................. 272 15.1.2. Underground mining................................................................................................................. 273 15.1.3. Alluvial mining............................................................................................................................. 274 15.3. Factors affecting mineral exploitation...............................................................................................274 15.4. The effects of mining to the economies of the world............................................................. 276 15.4.1. Positive effects of mining to the economies of the world............................................ 276 15.4.2. The negative effects of mining to the economic development of the countries of the world...................................................................................................................................................... 278 Case study......................................................................................................................................................... 279 Mining in the United States of America................................................................................................ 279 Factors influencing the development of mining in the USA.................................................... 280 Mining in the Middle East.......................................................................................................................... 281 Factors which have favored oil production in the middle East.............................................. 281 Problems facing the oil industry in the Middle East................................................................... 282 Mining in Zambia........................................................................................................................................... 282 x Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 Factors that favor the development of mining in Zambia........................................................ 283 Mining in Nigeria........................................................................................................................................... 283 Factors favoring the development of the mining industry in Nigeria................................. 284 xi Prepped by DUSABIMANA Jean D Amour. [email protected] Tel: 0780269676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool UNIT 1: STATISTICAL GRAPHS, DIAGRAMS, AND MAPS 1.1. Definition of statistics and importance of statistical graphs and diagrams in Geography 1.1.1. Definition of Statistics The term statistics refers to the science of collecting, analyzing, interpreting, and presenting various data. It is a science of how data are collected, analyzed, and interpreted. Statistics deals with data. Data is a word used to mean the information used as a foundation for reasoning, discussing and calculating. This implies that statistics and data go hand in hand. 1.1.2. Importance of statistical graphs and diagrams in geography Statistical graphs and diagrams play a key role in geography. They are needed in various aspects of human activities in this 21st century. They are important in the following ways:  Statistical graphs and diagrams help students to summarize huge and a wide range of information for future analysis. Diagrams and graphs hold huge information in accurate way.  The geographers can identify and interpret the relationship existing between various variables. For example, the relationship between the increase of prices for commodities and increase in cost of fuel.  Facilitate easy understanding of various geographical variables and clearly show the trend and variations of production, trade, among many others.  Statistical diagrams and graphs enable the learners to acquire various skills such as analytical skills, interpretation, and presentation of geographical data. Such skills can be used in other areas after school.  Most of statistical diagrams and graphs enable the students and geographers to save time as data is being recorded down.  Statistical graphs and diagrams provide a good and attractive visual impression. Therefore, arousing the interest of the reader or geographer in what is portrayed by the graph or diagram.  The data contained thereon the statistical graphs and diagrams, are used in making effective decisions. Therefore, logical judgmental conclusions are made based on factual data.  Statistical diagrams and graphs facilitate easy memory of the reader or students/geographers. Data and geographical information presented on diagrams and graphs are easily remembered than the data presented in a descriptive manner. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool  They help geographers to predict the trend of geographical events of various phenomena. For example, if a given graph shows a positive increase trend of coffee in country X, for some considerable years, it becomes easy to make predictions. 1.2. Line and curve graphs There are several types of line and curve graphs. They range from simple to more complexes depending on the composition and nature of the statistical data to be represented or portrayed. Under this category of statistics in Geography, the following are the main line graphs: a) Simple line and curve graph b) Group or comparative line graph c) Compound line graphs d) Divergence graphs. 1.2.1. Simple line and curve graphs A line graph is one which shows points plotted connected by a series of short straight lines. This distinguishes it from the simple curve graph in which points plotted are joined by a single smooth line. With line graphs points plotted are observable, while with curve graphs points are not noticeable. Another feature to take note of is; in a simple line graph, the line suspends without touching the two-vertical axis. On the other hand, in a simple curve graph, the smooth line drawn touches the two-vertical axis. Construction of a simple line graph The following are steps to be followed while constructing a simple line graph. The same applies to the drawing of a simple curve. These steps are stated here under: 1. The independent valuables are indicated on horizontal axis. (Independent valuables mean that when there is a change in the Independent variable or variables, results into a direct reaction of the dependent variables.) 2. The dependent variables are represented on the vertical axis. (Dependent variables are items that are reliant on the independent variables. That is to say; are measurable responses from the reaction caused by a change in the independent variables). 3. The vertical axis should start from Zero. While the top part be slightly greater than the maximum value to be indicated or recorded on it. 4. The length of the horizontal line is determined by the number of the independent values in relation to the scale 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool 5. Draw two vertical lines on both sides and exact numbers of values of constant relationship be recorded on the two axes. However, this is not necessary be done condition. 6. When plotting points in correspondence to both independent variables and dependent variables, it is appropriately to put the dot in the middle of the two vertical lines as shown below: Worked example Table 1. 1: The table showing temperature recorded at station B Months J F M A M J J A S O N D Temp. 0C 22 20 19 21 23 27 28 20 19 24 24 20 Use the data presented in the table above to answer the following the questions that follow: a) Construct a simple line graph to portray the above statistical data. b) Draw a simple curve graph to illustrate the above statistics shown on the table. Figure 1.1: Simple line graph of monthly mean temperature Advantages of simple line and simple curve graphs  They are simple to draw or construct.  When neatly drawn, they provide a good visual impression.  They are easy to interpret.  Less time is needed to construct them.  Simple errors or error free because of the simplicity nature of the methods.  Simple calculations are involved.  They can be used together with other statistical methods and diagrams such as dot maps, in a superimposition manner. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool  They have a multi-purpose service. For example, they are used in representing several geographical aspects such as the trend of crop production, variation in temperature, minerals, etc. Disadvantages of simple line and simple curve graphs  There is no accurate interpretation because of some points are plotted basing on estimation of values.  There are difficulties in determining the appropriate scale especially when large figures or values are used.  The curve graphs are less accurate in comparison to simple line graphs.  Not easy to use the simple line and curve graphs to compare various categories of data.  Changing scale of either axes, can greatly change the visual impression of the graph.  They are only used while dealing with continuous data. 1.2.2. Group or comparative graphs Group or comparative line graphs are known also as multiple line/curve graphs. This form of statistical method is used to portray more than one dependent variable. It is using several lines of which each represents a given specific variable of individual item. For group graph, the table has many dependent variables as shown below: Table 1.2: Crop production from 2012 to 2016 in Country X in „000,000 tons 2012 2013 2014 2015 2016 Coffee 19 15 45 82 109 Tea 50 36 30 70 80 Wheat 15 38 19 45 59 The above table shows several dependent variables as well as the independent variables. There are 5 years and three crops such as coffee, tea, and wheat. When critically analyzed, you find that for each independent variable in the left column (Crops) can be represented by a single simple line graph. The difference comes, with group graph or comparative graph; in this case, each crop will be represented on the same graph. As earlier said, a comparative line graph has several lines as shown by the sample hereunder: 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool Construction of group or comparative line/curve graph Below are steps or guidelines to be followed while drawing a Group or comparative/multiple line/curve graphs:  Several lines are constructed on the same graph.  The lines drawn representing individual variables or items should be easily distinguishable from one another. It is advised to use varying colors.  Avoid congesting the graph with many lines. The recommendable maximum number of lines is five. However, if the data given is having more than five independent variables that determine number of lines to be drawn.  The lines/curve should not cross each other unless the data given requires it. If it happens therefore, strictly varying colors or shading must be used.  Lines should not touch the vertical axis.  Names of variables being represented should be written directly on each line Worked example: Trends in the area cultivated („000 ha) for selected crops in country X Year Cash crops cereals Vegetables Fruits 2010 1110 786 700 150 2011 1230 840 720 250 2012 1330 850 790 100 2013 1290 900 800 150 2014 1396 950 830 56 Construction of a graph using the statistical data presented above. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool It is important to realize that lines are not crossing each other. The graph drawn shows that there was an increase in cultivated areas for all cash crops with exception for the area under fruits where a decreasing trend was observed. Advantages of group/comparative line graph  It is a simple method, as it does not involve many calculations.  It gives a clear impression of the different variables presented on one graph.  It can be used to show comparison of different items. Disadvantages of group/comparative line graph 1. The presence of many variables on the same graph makes their interpretation more difficult. 2. The values for each period are not easy to determine 1.2.3. Compound line graph A compound line graph is also known as a cumulative line graph. It is the type of graph where a variety of variables are presented as subsequent lines. Therefore, a compound line graph displays cumulative totals. It is drawn in a way that lines are super-imposed above each other; creating several segments or components. Construction of a compound line graph The listed below are steps that must be followed while constructing a compound line graph:  Make a cumulative table representing progressive or cumulative totals of the provided variables.  Select the appropriate scale for both dependent and independent variables.  Follow the steps used when a simple line graph is being drawn. It should be the variables with large or biggest values to begin. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool  The lines constructed for each variable should connect onto the two vertical lines on both sides.  Super-impose other lines on top of the first line beginning from each segment or component. Indicate the name of the variable in each section shaded.  The lines drawn must begin from or attach to the vertical axis as earlier emphasized.  Since plotting of points is dependent on the calculated values in a cumulative manner, lines therefore, must not cross each other. In case they do so, then, the data given, or the calculated cumulative totals will be having a problem.  If the statistical data is in large numbers, it is very advisable to covert the value of each variable into percentage. Thereafter, calculate the cumulative totals. Such calculations should be indicated. Worked example: Table 1. 4: Table of total exports in million tons for country X for 2015-2017 2015 2016 2017 Crops Cocoa 46.0 74.0 69 Cassava 11.0 24.5 27.7 Beans 13.0 11.5 33.3 Use the data presented in table above to construct a compound line graph Table 1.5: Table of cumulative total exports in million tons for country X from 2015-2017 Years 2015 2016 2017 Crops Cocoa 46.0 74.0 69 Cassava 57.0 98.5 96.7 Beans 70 110 130 The above cumulative totals can now be used to construct a compound line graph; as shown below: Compound line graph showing cumulative total exports for country X for 2015-2017 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool Advantages of Compound line graph  They are easy to interpret.  They provide a good visual impression.  They are simple to draw.  Less space is used.  They can be used to present a variety of variables.  They are suitable for comparison purposes. Disadvantages of compound line graph  When large numbers are used, selecting a suitable scale becomes more challenging.  It or they involve calculations such as; converting the values into percentages and then determining the cumulative totals.  The use of cumulative totals while constructing the compound line graphs makes it difficult to find precisely the actual values of the variables. 1.2.4. Divergence line graphs Divergence line graphs are statistical graphs that directly portray variations in values. When there is a rise in values; a plus sign (+) is used in the figure while and fall or decrease in values is portrayed using a negative sign (-). This type of graph is used while dealing with variables whose values are highly changing spatially and temporally. Construction of a divergence line graph There are six steps to follow when one is drawing a divergence line graph. These are:  Draw two vertical lines (axis) and leave a reasonable space for the baseline; on which the independent variables are to be indicated.  Draw the average line commonly known as the zero line. This should join the center of the two-vertical axis.  Draw a basement line for independent variables; joining the bases of the two vertical lines. The length of the horizontal line is determined by the number of independent variables and the horizontal scale used.  Determine the average values of all the values indicated in the table. This is obtained using the following formula  Deduct the average value from each value. The positive and negative signs should be indicated or shown.  The figures or values with positive sign (+) are plotted above the Zero line or average line. While the negative values are plotted below or beneath the zero or average line.  While determining the scale, the vertical scale should be determined basing on the calculated divergences. The horizontal scale is chosen normally depending on the independent variables provided. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool  Thicken or darken the zero line/average line. Worked example: Table 1.7: The table of monthly pineapple production in different areas Areas Monthly production in ‘000 tons A 10,527 B 10,038 C 3920 D 3770 E 2550 F 1833 G 884 H 825 I 744 Table 1.8: The table of monthly pineapple production in different areas Area Monthly production in Divergence values „000 tons A 10,527 -3 ,910.11 +6618.89 B 10,038 - 3,910.11 +6127.89 C 3920 - 3,910.11 +9.89 D 3770 - 3,910.11 -140.11 E 2550 - 3,910.11 -1360.11 F 1833 - 3,910.11 -1977.11 G 884 - 3,910.11 -3026.11 H 825 - 3,910.11 -3085.11 I 744 - 3,910.11 -3166.11 A divergence line graph showing monthly pineapple production in different areas 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool Divergence line graph of monthly pineapple production in different areas Advantages of divergence line graph Below is an outline of the main advantages of divergence line graph:  Easy to construct  Provides a good visual impression  Easy to interpret  They are appropriate method of representing items that need comparative analysis.  Limited space is used. Disadvantages of divergence line graph They involve several calculations for example the total value, getting average, finding divergences.  The actual figures are not shown, only divergences are indicated instead  There are some difficulties while determining the scale mostly when the divergences are composed of bigger values and very low ones.  They are time consuming.  The method allows some inaccuracy while being drawn. This is because if large values are used, decimal points are neglected  To be used requires the reader to have the original raw data or a table of values. 1.3. Bar Graphs Bar graphs are one of the statistical methods used to show or portray or represent data. It is a graph constructed using rectangular bars. Bar graphs differ from line graphs because the lines used under bar graphs join to form single and individual rectangular bars. This means that bar graphs stand for a graphic way of numerical (quantitative) comparison by rectangles with heights proportional to the measure of data in question. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool 1.3.1. Simple bar graphs A simple bar graph is created following the same procedures as a simple line graph. However, instead of using a line to represent the variables, parallel bars are used. The independent variables are indicated on the horizontal axis and dependent variables shown on the y axis or vertical line. This form of statistical graph is constructed when a single set of statistical data is used. Construction of a simple bar graph The following are the main steps followed to construct a simple bar graph:  Create a frame of both vertical and horizontal axes. That is, drawing the X and Y axes. The length of these two lines will be determined by the scales used and the figures to be plotted.  Indicate the independent variables on the X axis and dependent variables on Y axis.  Select appropriate scale: Both vertical and horizontal scales. This is determined as studied while dealing with line graphs.  The horizontal scale will automatically determine the size of the bars. It is recommended that the size of each bar should not exceed 1 cm or go below 1cm in width. Too small and huge bars make the graph lose its primary appearance.  While plotting points, use tiny dots to mark the required points. This so because with bar graphs dots are not supposed to be seen.  The volume, percentage or value of the dependent variable, is represented by the height of each independent bar.  A reasonable small space should be left to separate the bars from the vertical axis.  There should be uniformity in terms of the size of bars, separating space existing between bars  The bars should be attached only when a single or similar dependent variable is being dealt with. But this is not a golden ruling. For example, Rainfall, production of coffee or any other variable. Worked example Table 1. 9. Table of annual mean rainfall at Kanombe weather station Months J F M A M J J A S O N D Rainfall 10 17 18 45 102 170 159 117 78 45 22 10 in mm The data displayed in table above were used to construct the following simple bar graph: 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool A simple bar graph showing annual mean rainfall (dependent variables) at Kanombe weather station The data used to construct the above simple bar graph, deals with single dependent variables like rainfall and that is why the bars are attached to each other. However, the separated bars are used to represent independent variables as shown on the figure below. Table showing the profits made in a period of 5 years by company Umubanomwiza Years 2012 2013 2014 2015 2016 Profit in million 10 12 18 25 42 Rwf The above data are used to construct a simple bar graph for independent variables as shown below: A simple bar graph showing profits made by Umubanomwiza Company (independent variables) 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool Advantages of simple bar graphs The following are advantages of simple bar graphs:  They are easy to interpret  Summarizes a large amount of data in a visual form  They display trends easier to highlight or notice than simple line graphs.  They can be super-imposed on other statistical diagrams. That is, they can be used together with other methods.  They are easy to construct  They do not involve complicated calculations.  They represent each data category in a frequency distribution  The several bars constructed provide a chance of comparative analysis and expression of differences existing between variables. For example, rainfall received within 12 months.  They provide a compact way of presenting statistical data  They are suitable for showing data with different units such as years, months among many others. Disadvantages of simple bar graphs  They can easily be manipulated to provide false impressions.  When large figures are used, determining a suitable scale challenges.  Time consuming especially when several variables are dealt with  They do not provide adequate explanation. Therefore, for them to be rewardingly understandable, additional explanation is required.  Simple bar graphs do not show key assumptions, causes, impacts, and patterns. 1.3.2. Group bar graph Group bar graphs also known as multiple bar graphs. Group or multiple bar graph, is a statistical technique used to represent data that is made up of several dependent variables, that can hardly be shown using simple bar graph. A group of bars is constructed following the steps involved in drawing of a simple bar graph. The only difference is that group bar graph is constructed by attaching a set of bars representing individual variables. Construction of a group bar graph The following are main steps involved in construction of a group bar graph:  The way of constructing a group bar graph is the same as that of simple bar graph.  The bars are drawn in form of a set and touching each other for each independent variable. This implies that bars are grouped but separated from another group by a space  Draw the bars in a vertical manner. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool  The independent variable that has the largest values should be started with and drawn on the left and continuing in a descending order towards the right  The arrangement of the first group should be maintained throughout  The width of all bars must be similar. That is, ensure that all bars display equal size.  Shade differently each individual bar and maintain the same shading or coloring up to the last group of bars.  A suitable title as adapted from the title of the table used should be indicated on top part of the graph. Advantages of group bar graph In the advantages of group bar graph  It is easy to interpret.  It favors comparative analysis of the statistical data being dealt with.  It is simple to draw.  The calculations involved are simple and easy.  It provides a wonderful visual impression when it is colored.  It can be used together with other diagrams in a super-imposed way.  It is suitable for a wide range of variables. Disadvantages of group bar graph  It requires a large space  It is challenging while determining the scale.  It may be difficult to interpret it when it is congested. 1.3.3. Compound bar graph Compound bar graphs are also called cumulative or divided bar graphs. This form of statistical graph is used to show how the total in any one bar is divided up between several subtotals basing on the calculated cumulative totals. This implies that the totals used to plot the variables are progressive in nature. A compound bar graph used when there is more than one variable and a variety of the items are to be portrayed using one bar. Basing on cumulative totals as calculated depending on the raw data on the table provided, a given a bar can be divided into segments. The size of each segment depends on the value of variable being represented. Construction of a compound bar graph The following are the main steps followed to construct compound bar graph:  It is constructed by using cumulative progressive totals.  It requires selecting a suitable scale that can favor the plotting of both big and small values. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool  The plotted data are displayed in percentages by starting with the greatest value and ending with the smallest figure.  The width of each bar is determined basing on the scale used.  The number of bars will be determined by the number of variables to be represented in each set of bars.  The varying sheds or colors are used for each individual segment or component of every bar. Worked example: Table 1. 12: Coffee and tea production in 000 tones for selected regions in 2017 Regions/ Cash Crops Coffee tea Girubuntu 2206 2535 Ubumwe 786 708 Ubusugire 1295 1928 The above data are used to construct a compound bar graph as shown below: Compound bar graph of coffee and tea production for selected regions 1.3.4. Divergence bar graphs The primary purpose of the divergence bar graph is to represent the way values of various variables deviate from the average/mean value. Therefore, this statistical method shows the fluctuation of the variables. Construction of divergence bar graphs The steps to be followed while constructing divergence bar graph are:  Construct the two vertical axis lines. Draw the vertical.  Join the two vertical lines with the horizontal line at the base line. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool  Draw the average line which is known as a zero line at the center of the two vertical lines. Write the average against this line at the end points where  Find the total of all the value of the variables and divide it by the number of the items, to get the average. Subtract the average obtained from each value, to get the divergences or deviations.  Select the suitable scale basing on the divergences calculated.  Plot the negative values below the average line and the positive ones above the same line. Worked example: Table 1. 13: Country’s coffee production in 000 tons Year Coffee production in „000 tons 2010 500 2011 600 2012 900 2013 700 2014 800 2015 700 2016 560 2017 600 (a) Calculate the average value 500+600+900+700+800+700+560+600 =670 8 Divergences from the mean Year Value Average Divergences from the mean value 2010 500 670 -170 2011 600 670 -70 2012 900 670 +230 2013 700 670 +170 2014 800 670 +130 2015 700 670 +170 2016 560 670 -110 2017 600 670 -70 The following divergence bar graph showing country’s coffee production in 000 tons from 2000-2008 is drawn using the data presented in table above. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool A divergence bar graph showing divergences in country’s coffee production Advantages of divergence bar graphs The following are advantages associated with divergence bar graphs:  Provides a good visual impression  They are appropriate for comparison purposes.  They are easy to construct  They are less complex therefore, easy to interpret.  Limited space is used. Disadvantages of divergence Bar Graphs  There are several calculations involved.  The method is only limited to a single item or commodity.  Determining the scale especially when the values have a wider amplitude is challenging.  The plotting of values is only based on divergences. Therefore, the actual values are not seen. 1.3.5. Age and sex graphs An age-sex graph is also known as a population pyramid. It is a type of bar graph that represents the structure of the population of a country or area basing on age and sex. An age-sex graph forms a structure of pyramid as the population grows. It is a graphical drawing that displays the distribution of several age groups in each population of a country or part of the world, which makes the shape of a pyramid as the population grows.  It typically involves two back to-back bar graphs, with the population plotted on the horizontal line and age on the vertical line.  The left side of the population pyramid should indicate the Male and the right for Females.  It is usually in age groups of five years for example 0 - 4 years; 5 - 9 years; 10 - 14 years and so on. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool  The age groups are indicated or plotted in the middle Therefore, the primary purpose of the population pyramid is to portray population structure and age groups. The number may be in a raw form or converted into percentages. Population pyramids are often regarded as the most actual way to graphically represent the age and sex distribution of a population. This is so, because of its clear visual interpretation and direct display of the true picture of the real structure of the population. Construction of age-sex graph When drawing an Age-sex pyramid, the following steps should be observed:  It is constructed on two X- axis; one to portray male and another for females.  Males are represented on the left and females on the right. The bars representing each sex are separated by a space. It is in this space that age groups are indicated in a progressive manner.  The data provided should be grouped using the interval of 5 years as follows; 0 - 4; 5 – 9; 10 – 14; 15 – 19; 20 – 24; 25 – 29; 30 - 34 and so on.  After forming the age groups; the lowest group which forms the youngest is indicated on the base of the graph.  The left horizontal line should have figures for males and the one on top the right shows the figures for females. Worked example: Table 1. 15: Table showing population structure (age-sex) of country X Age Male Female 0-4 4500 4780 5-9 4280 4400 10-14 3980 3050 15-19 3400 3000 20-24 2540 2300 25-29 2050 1809 30-34 1940 1920 35-39 1800 1750 40-44 1500 1670 45-49 1200 1300 50-54 1050 1290 55-59 800 900 60-64 500 700 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool 65-69 450 656 70-74 300 478 75-79 120 140 80-84 87 130 85+ 40 80 The following age-sex bar graph of country X is drawn using the data presented in table above. Age-sex graph of country X Advantages of an age-sex graph The following are the main advantages of an age-sex graph:  It provides instant display of the composition of population being portrayed with consideration of the age and sex.  It portrays the general shape of population structure that facilitates analytical purpose.  The features associated with the age-sex pyramid can indicate factors affecting an area or region it presents.  It gives a good visual impression that captures the attention of the reader or interpreter.  It is easy to interpret  It has limited or sometimes no calculations involved, therefore, it is easy to draw.  Age-sex pyramid is suitable for comparison purposes. For example, the number of females and male in each area. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool Disadvantages of an age-sex graph  It is only used to represent population structure.  It is only used alone and hardly super-imposed on other methods.  There is loss of vital information due to the use of figures that are in age- cohorts.  It cannot show the population distribution (Do not describe or show the trend of population growth).  It is only used in population geography.  The actual figures may not be seen since in most cases percentages are used.  It takes a lot of time while constructing.  It takes a lot of space.  It is challenging to determine a suitable scale. 1.4. Simple divided circles A circle is drawn to represent statistical data given as a whole. The circle is then divided according to the value of the variables. Construction of a simple divided circle The following are steps that are followed in constructing a simple divided circle:  Draw a circle of a reasonable size. Avoid using small or very big circles.  Determine the degrees proportional to the quantity, value, amount, of the item or component to be portrayed.  Start with the component with the biggest degree. Place this to the right of 12o’clock.  Arrange the smallest portions or segments to be plotted in one part. That is, start from the biggest to the very tiny segment.  Labeling on a pie chart should take a horizontal order. Where need be, write the words or names outside the chart using a pointing arrow for the small segments.  Shed each segment different and use the key for referral purpose. If colors are available, use them.  The segments or components should not go beyond 8 in number. Beyond this figure, the chart becomes over crowded or jam-packed. Worked sample: Table showing the exports of country X (1) Items Exports (‘000 tons) Yellow banana 894 Pineapple 456 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool Cereals 286 Beans 189 Vegetables 105 The data presented above were used to construct a simple divided circle. The presentation of the data displayed in table above on simple divided circle requires calculating the values of each data in degrees. These calculated degrees can be also changed or converted into percentages. Table showing the exports of country X (2) Items Exports (‘000 tons) Degrees Yellow banana 894 166.75° Pineapple 456 85.05° Cereals 286 53.34° Beans 189 35.25° Vegetables 105 19.58° The above calculated degrees are used to construct the simple divided circle as shown below. A pie chart showing exports of country X in 000,000 tons Advantages of a simple divided circle/pie chart Simple divided circles or pie charts are increasingly becoming a common tool used in representation of statistical data. This is because of its advantages as shown below: 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool  When the wedges are clearly shaded or colored, they provide a good visual impression.  They are effective and reliable when two or more variables are to be comparatively analyzed.  When well-labeled, they are easy to interpret.  They don’t require specific skills to be understood as it is the case of dispersion graphs, divergence graphs, among many others.  They involve simple calculations which make them to be easy to draw.  Pie charts can be super-imposed on other statistical methods such as maps.  They can be used for a wide range of purposes in geography and other disciplines.  Pie charts are used as a summarizing tool, where vast data is set in a visual way.  The divided circles require minimal additional explanation or description. Disadvantages of a simple divided circle/pie chart  They deal with degrees and sometimes percentages. Therefore, exact figures may not be easily being noted by the reader.  Pie charts are not suitable for tracking the trend of a given variable. This implies that, several pie charts must be used.  Pie charts can easily be maliciously manipulated or intentionally altered, therefore, displaying incorrect information. Hence, the reader may make erroneous conclusions.  They are constructed without basing on a specific scale. Such leaves a gap in the exactness of the method.  They provide errors, due to lack of accuracy; especially when tiny degrees are plotted. The thickness of the pencil affects the perfection of the method.  Labeling the pie chart sometimes is challenging especially when small degrees are plotted.  Pie charts or divided circles take a lot of time to construct. This is because of the calculations, measuring, drawing, and shading.  Large wedges/segments for bigger values tend to over shadow the small values.  In case there several segments of almost matching size, it is challenging and confusing or difficult to interpret and assimilate the data.  The reader may find it challenging to comparatively analyze non-adjacent segments. That is, the reader will keep twisting and turning the chart to have a suitable angle of observation. 1 Prep ed b p y DUSAB IMA NA J ean D Am jour. ohnmqu c ig@g ml.ca m T o el: 07 2680 9676 DU SABI MA NA Je an D Am our St. P aul In tern ation al Sc hool UNIT 2: BEARINGS, DIRECTIONS, DISTANCES AND AREAS ON A MAP 2.1. Location of places using the grid reference A grid is a series of straight lines drawn vertically and horizontally on topographical maps. Where the lines cross each other, they form squares of equal sizes.  The lines running from north to south (vertical lines) are called Eastings. This is because their numbers increase towards the east from the south western cor

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