1. Chapter 3
Visual Display of Data

2. Frequency Tables Binning Data Class Freq 0-9 2 10-19 5 20-29 7
Grouping/categorizing data
Each bin(group) covering a range of the possible data values
Class
Freq
0-9 2
10-19 5
20-29 7
30 or more 6
Total 20

3. Relative Frequency
The proportion or percentage of the data values that fall in that category(group)
Grade
Freq
Relative Freq A 4
0.16 B 7
0.28 C 9
0.36 D 3
0.12 E 2
0.08
Total 25
1.00

4. Cumulative Frequency
The number of data in that category(group) and all preceding categories
Grade
Freq
Cum. Freq A 4 B 7 11 C 9 20 D 3 23 E 2 25
Total

5. Exercise
Exercises with Excel

6. Picturing Distributions of Data
The way values are spread over all possible values.
Summarizes with table or graph

7. Graphs Title/Caption Vertical Scale & Title Horizontal Scale & Title
Legend
Bar graphs
Bars representing frequencies (or relative frequencies) for particular categories. Bar lengths are proportional to the frequencies
Dotplots
Data value is represented with dot
Pareto Charts
A bar graph with bars arranged in freq order. Only make sense for data at the nominal level measurement

8. Graphs (cont.) Pie Charts Histograms
A circle divided so that each wedge represents the relative frequency of a particular category
Histograms
A bar graph showing a distribution for quantitative data (at the interval or ratio level of measurement)
The bars have a natural order and the bar widths have specific meaning

9. Graphs (cont.) Stem-and-leaf plot Line Charts (Frequency Polygon)
Like a histogram turned sideways
A listing of the individual data sources or values instead of bars
Line Charts (Frequency Polygon)
A distribution of quantitative data as a series of dots connected by lines.
For each dot, the horizontal position is the center of the bin it represents and the vertical position is the frequency value of the bin

10. Graphs (cont.) Time-Series Diagrams
A histogram or line chart in which the horizontal axis represents time

11. Exercise
MS Excel

12. Graphics in the Media Multiple Bar graphs and Line Charts Stack Plots
Multiple sets of data displayed on the same chart for comparison purpose
Stack Plots
Multiple sets of data stacked (as columns)
Geographical Data
Contour map
Three-Dimensional Graphics
Complex Graphics

13. Exercises
Ex17-19 pp (MS Excel)

14. A few cautions about graphics
Perceptual Distortions
Length, height, area, volume
Watch the scales
Uniform/non-uniform scale
Stretched/compressed scale
Unadjusted Economic Data
Effect of inflation
The real cost

15. A few cautions about graphics (cont.)
Percentage change graphs
Downward-sloping lines show that the rate of percentage increase slowed, not that the actual value went down
Pictographs
More appealing
But can also distract or misled

16. Focus on Environment
How Can We Visualize Global Warming? pp