1. Describing Data Visually3
Describing Data Visually
Chapter
Visual Description
Dot Plots
Frequency Distributions
and Histograms
Line Charts
Bar Charts
Scatter Plots
Tables
Pie Charts
Descriptive Graphs
McGraw-Hill/Irwin
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved. 1

2. Visual Description
Methods of organizing, exploring and summarizing data include:
- Visual (charts and graphs) provides insight into characteristics of a data set without using mathematics.
- Numerical (statistics or tables) provides insight into characteristics of a data set using mathematics. 2

3. Dot Plots Comparing Groups
A stacked dot plot compares two or more groups using a common X-axis scale. 3

4. Frequency Distributions and Histograms
A frequency distribution is a table formed by classifying n data
values into k classes (bins). 4

5. Frequency Distributions and Histograms
A histogram is a graphical representation of a frequency distribution.
Y-axis shows frequency within each bin.
A histogram is a bar chart.
X-axis ticks shows end points of each bin. 5

6. Frequency Distributions and Histograms6

7. Frequency Polygon and Ogive7

8. Line Charts Simple Line Charts
Two-scale line chart – used to compare variables that differ in magnitude or are measured in different units.
A line graph usually has no
vertical grid lines. Horizontal
lines can be added to make it
easier to establish the y value. 8

9. Line Charts
Log Scales
Log scale is only suited for positive data values.
Reveals whether the quantity is growing at an increasing percent (concave upward), constant percent (straight line), or declining percent (concave downward) 9

10. Bar Charts Plain Bar Charts
Most common way to display attribute data. - Bars represent categories or attributes. - Lengths of bars represent frequencies.
Vertical Bar Chart
Horizontal Bar Chart 10

11. Bar Charts Pareto Charts
Special type of bar chart used in quality management to display the frequency of defects or errors of different types.
Categories are displayed in descending order of frequency.
Focus on significant few (i.e., few categories that account for most
defects or errors). 11

12. Scatter Plots
Scatter plots can convey patterns in data pairs that would not be apparent from a table. 12

13. Tables Tables are the simplest form of data display.
A compound table is a table that contains time series data down the columns and variables across the rows. 13

14. Pie Charts Pie Chart Options
Exploded and 3-D pie charts add strong visual impact but slices are hard to assess.
Exploded Pie Chart
Exploded 3-D Pie Chart

15. Effective EXCEL Charts
Effective visual displays help you get your point across and persuade others to listen to your point of view.
Powerful graphics stands out in reports which helps in better decision making.
Excel is widely used primarily because of its excellent graphics capabilities.
Excel offers a vast array of charts.
You need to experiment in creating graphs with Excel to get familiar with its features and how you can create effective graphs.

16. Deceptive Graphs Error 1: Nonzero Origin
Error 2: Elastic Graph Proportions
Error 3: Dramatic Title
Error 4: Distracting Pictures
Error 5: Authority Figures
Error 6: 3-D and Rotated Graphs
Error 7: Missing Axis Demarcations
Error 8: Missing Measurement Units or Definitions
Error 9: Vague Source
Error 10: Complex Graphs
Error 11: Gratuitous Effects
Error 12: Estimated Data
Error 13: Area Trick 16