Colorado State University — Pueblo; Fall 2015
Math 156: Introduction to Statistics
Applied Statistical Exegesis Example 1

Source

Here they are:

Explanation

• The individuals were, in theory at least, all humans on planet Earth. [In practice, they must have done some sort of survey.]
• The variable associated with these individuals was their religious affiliation. This is a categorical variable.

The second graph consists of four side-by-side bar graphs.

• The individuals were, for each bar graph, all humans a particular country (again, in theory).
• The variable associated with these individuals was their religious affiliation. This is a categorical variable.

Critique

The graphs are all nicely and completely labelled, with sufficient resolution and detail. All the terms — the particular values of the categorical variables — are completely explained.

The side-by-side bar graphs were a good choice for the second graph: they allow a more direct comparison of the values in a particular category across the four countries shown.

I wonder how they got their data: sampling, I presume, but are they sure they got representatives from all religious groups in representative proportions? Maybe some minority religious groups keep very isolated and are therefore hard to locate and survey. In addition, in some countries it may be hard to get people to respond truthfully to a question about their religion — Jews in Nazi Germany or Fredinand and Isabella's Spain would not have told the truth about their religion; Christians may not tell the truth in China or Iran today. So I worry a little about the quality of this data.