Data Visualization PDF

Data Visualization IT1164/IT1364/IT1564/IT1664/IT1864/IT1964 Learning Outcome Illustrate the use of various 1 charts for visualizing different types of data 2 Types of Data Qualitative Quantitative...

Data Visualization IT1164/IT1364/IT1564/IT1664/IT1864/IT1964 Learning Outcome Illustrate the use of various 1 charts for visualizing different types of data 2 Types of Data Qualitative Quantitative Nominal Discrete Ordinal Continuous 3 Nominal Data  Nominal scales are used for labeling variables, without any quantative value, also known as “labels.”  The scales are mutually exclusive (no overlap) and none of them have any numerical significance. A good way to remember all of this is that “nominal” sounds a lot like “name” and nominal scales are kind of like “names” or labels. 4 Ordinal Data  The order of the values is important and significant, but the differences between each one is not really known. Refer to example below, #4 is better than a #3 or #2, but we don’t know– and cannot quantify–how much better it is. For example, is the difference between “OK” and “Unhappy” the same as the difference between “Very Happy” and “Happy?” We can’t say.  Ordinal scales are typically measures of non-numeric concepts like satisfaction, happiness, discomfort, etc.  “Ordinal” is easy to remember because is sounds like “order” and that’s the key to remember with “ordinal scales”–it is the order that matters. 5 Discrete Data  It means distinct or separate i.e data that relies on counts.  It contains only finite values i.e values that can only be counted in whole numbers or integers and cannot be broken down into fraction or decimal.  For example, Number of students in the school, the number of cars in the parking lot, the number of computers in a computer lab, the number of animals in a zoo, etc. 6 Continuous Data  It is an unbroken set of observations; that can be measured on a scale.  It can take any numeric value, within a finite or infinite range of possible value.  The continuous data can be broken down into fractions and decimal, i.e. it can be meaningfully subdivided into smaller parts according to the measurement precision.  For Example, Age, height or weight of a person, time taken to complete a task, temperature, time, money, etc. 7 Commonly-used Chart types  Vertical Bar Chart  Horizontal Bar Chart  Histogram  Line Chart  Pie Chart  Scatter Plot Chart  Bubble plot  Word cloud  Area Chart L2: Data Visualization & Dashboards Types of Charts 1. Vertical Bar charts  best for comparing average or percentages between 2 to 7 different groups.  x-axis – mainly for mutually exclusive categories (like multiple choice, or check box questions). 9 Types of Charts 2. Horizontal Bar charts  best for comparing average or percentages of 8 or more different groups.  x-axis – mainly for mutually exclusive categories (like multiple choice, or check box questions). 10 Types of Charts 3. Histogram  to illustrate sample distributions on dimensions measured with discrete intervals.  x-axis – categories that are based on a continuous scale. 11 Types of Charts 4. Pie Charts  best used to illustrate the proportion within groups based on one variable.  pie charts should only be used with a group of categories that combine to make up a whole. 12 Types of Charts 5. Line Charts  illustrate trends over time.  to compare two different variables over time. 13 Types of Charts 6. Scatter Plots  2D plot showing the joint variation of two data items.  scatter plots are useful for examining the relationship, or correlations, between X and Y variables. 14 Types of Charts 7. Bubble Plots  A bubble plot displays the relationships among at least three measures.  Two measures are represented by the plot axes. The third measure is represented by the size of the bubbles 15 Types of Charts 8. Word Cloud  used on unstructured data as a way to display high- or low- frequency words. 16 9. Area Chart Monthly Price Difference for XYZ  To show the magnitude of change between two or more data points. Example  A visual feel for the degree of variance between the high and low price for each month L2: Data Visualization & Dashboards What is an appropriate chart? Nominal Comparison 160000 140000 2003 Sales by Region 120000 100000 Answer: 80000 60000 Bar or column chart 40000 20000 0 North South East West How about a line chart? Line chart not appropriate because the slope of the line as it moves from data point to data point would suggest change between different instances of the same measure. The movement from one region’s sales to the next does not represent a change. L2: Data Visualization & Dashboards What is an appropriate chart? Time Series 2003 Sales by Month 3500 3000 2500 Answer: 2000 1500 Line chart 1000 500 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Lines do a great job of showing the flow of values across time, such as consecutive months of a year. The movement from one value to the next in this case represents change, giving meaning to the slope of the line: the steeper the slope, the more dramatic the change. L2: Data Visualization & Dashboards What is an appropriate chart? Part to whole Percentage of Sales by Region 22% Answer: 39% North South Pie chart 17% East West 22% The individual slices of a pie chart add up to make up the whole pie (100%). Bar or column chart may be used to show percentages as well but the fact that the individual bars add up to 100% is not as obvious. L2: Data Visualization & Dashboards What is an appropriate chart? Whole and its parts 120000 2003 Sales by Region and Quarter 100000 80000 Answer: West 60000 East Stacked bar or South 40000 North column chart 20000 0 Q1 Q2 Q3 Q4 Stacked bar or column charts are the right choice when you must display multiple instances of a whole and its parts, with emphasis primarily on the whole. L2: Data Visualization & Dashboards What is an appropriate chart? Correlation Correlation of Radio Ads and Sales Revenue 12000 Answer: Monthly Sales Revenue ($) 10000 8000 XY scatter plot 6000 4000 2000 0 0 2 4 6 8 10 12 Monthly Total of Radio Ads Displays whether or not, in what direction, and to what degree 2 paired sets of quantitative values are correlated. L2: Data Visualization & Dashboards THANK YOU