Data Management 1 Lecture Notes PDF

Data Management 1 JO-ANN C. GARCIA, MATM Re-echo  STATISTICS Is the branch of science that deals with the collection, presentation, organization, analysis and inter...

Data Management 1 JO-ANN C. GARCIA, MATM Re-echo  STATISTICS Is the branch of science that deals with the collection, presentation, organization, analysis and interpretation of data Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-2  DATA Are the facts and figures collected, analyzed and summarized for presentation and interpretation Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-3  POPULATION - Is the collection of all elements under consideration in a statistical inquiry - Consists of all subjects under study Sample- is a subset of the population Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-4  TYPES OF STATISTICAL ANALYSIS  Descriptive Statistics- are used to describe the basic features of the data in a study. They provide simple summary about the sample and the measures.  Inferential Statistics- includes all the techniques used in analyzing the sample data that will lead to generalization about a population from which the sample came from Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-5  VARIABLE  Is a characteristics or attributes of the elements in a collection that can assume different values for the different elements. Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-6  MEASUREMENT  Is the process of determining the value or label of the variable based on what has been observed Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-7  DATA GATHERING TECHNIQUES Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-8  1. SOURCES OF DATA  Primary Data- it includes government agencies, business establishments, organizations and individuals who carry original data or who have the firsthand information relevant to a given problem  Secondary Data- data obtained from secondary source like newspapers, magazines, journals and republished materials. Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-9  2. METHODS OF COLLECTING DATA a. The Interview Method- is a person-to-person encounter between the one soliciting information and the one supplying the data. It could either be personal interview or a telephone interview. b. The Questionnaire Method- it utilize questions to obtain information. They are either mailed or hand-carried to the intended participants. c. The Observation Method- data pertaining to behaviors of an individual or a group of individuals at the time of occurrence of a given situation are best obtain by direct observation. Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-10  2. METHODS OF COLLECTING DATA d. The use of Documents- researchers who make use of vital statistics, such as the number of households, birth rates, death rates and marriages. e. The Method of Experimentation- data needed to answer questions through series of experimentations. Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-11  3. METHODS OF PRESENTATION Statistical data collected should be arranged in such a manner that will allow a reader to distinguish their essential features a. The textual form- this is utilized when the data to be presented are purely qualitative or when very few number are involved. b. The tabular form- it is used when people want to make comparisons and draw relationships. c. The graphical form- the graph or chart is perhaps the most effective device for attracting people attention. Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-12  VARIOUS TYPES OF GRAPHS a. Line Graph b. Bar Graph c. Component Bar Graph d. Pie Chart e. Pictograph f. Statistical Maps Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-13  SAMPLING TECHNIQUES Target Population- is the population we want to study Sampled Population- is the population from where one actually select the sample Probability Sampling- is a method of selecting a sample wherein each element of the population has a known, nonzero chance of being included in the sample Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-14  Measures of Central Tendency Measures of central tendency are descriptive measures that are used to describe the center of a set of data. 1. The arithmetic mean is the most common type of average. It is the sum of all the observed values divided by the numbers of observations. 2. The median is the value that divides the array into equal parts. 3. The mode is the observed value that occurs with the greatest frequency in a data set Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-15  Measures of Location Measures of Location on positive fractiles are used to specify the location of specific data in relation to the rest of the sample. It divides the distribution into equal number of parts. 1. The percentiles divide the ordered observation into 100 equal parts. 2. The quartiles divide the ordered observations into 4 equal parts. 3. The decile divides the ordered observation into 10 equal parts.  Measures of Dispersion Measures of Dispersion or Variability describes the spread or the scatterings of the values around the mean. 1. The range is the distance between the maximum value and the minimum value. 2. The variance is the average squared difference of each observation from the mean 3. The standard deviation is the positive square root of the variance 4. The coefficient of variation is the ratio of the standard deviation to the mean, expressed as a percentage Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-17  Measures of Skewness Measures of Skewness measures the degree of symmetry of a distribution. sk = 0, symmetric distribution sk > 0, positively skewed distribution sk < 0, negatively skewed distribution Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-18  Measures of Skewness 1. Symmetrical or Normal Distribution In a symmetrical distribution the mean, median and mode all fall at the same point or equal. 2. Positively Skewed Distribution In a positively skewed distribution the extreme scores are larger, thus the mean is larger than the median 3. Negatively Skewed Distribution The order of the measures of central tendency would be the opposite of the positively skewed distribution with the mean being smaller than the median, which is smaller than the mode Statistics for Managers Using Microsoft Excel, 4e © 2004 Prentice-Hall, Inc. Chap 12-19  Symmetric Distribution  zero skewness mode = median = mean  Right Skewed Distribution  positively skewed: Mean and Median are to the right of the Mode.  Mode