Identifying Misleading Graphs
Graphs are pictorial representations of numbers. Therefore, at the least, we should expect that the representation of the numbers be proportional to the numbers themselves. Unfortunately, this is not always the case. In some cases this occurs because the graph designer wants to give the impression of better performance than is actually the case. In other cases, the designer might not have any numerical sense.
Figure 1. Source: Erickson Times
Figure 1, which appeared in Erickson Times, shows the number of Olympic medals won by country. For Germany, the picture of two medals corresponds to almost 500 medals. Therefore, we would expect the picture of four medals to correspond to almost 1000 medals and the picture of six medals to correspond to almost 1500 medals. However, the label for the four-medal picture is 615 and for the 6 medal picture is 1975. Although there is the correct rank ordering, there is little relationship between the pictures of the medals and the labels of the number of medals.
Misleading Graphs and Statistics
It is a well known fact that statistics can be misleading. They are often used to prove a point, and can easily be twisted in favour of that point! The purpose of this section is to learn how to recognize common statisitcal deception so that to avoid being mislead.
When you use a sample to represent a larger group, you must make sure that the people in the sample are fairly representative of the larger group. Example 31.1
Decide whether a mall is a good place to find a sample for a survey about the amount of allowance received by people ages 10 to 15.
The mall is probably not a representative place to find a fair sample of people in this age range. Taking a sample at the mall might not represent fairly those people who receive a small allowance, or none
Good graphs are extremely...