Colorado State University — Pueblo; Fall 2014
Math 156: Introduction to Statistics
Applied Statistical Exegesis Example 1
Source
I am looking at the first two graphs in the Pew Research Center's report
Global Religious Diversity, which can be found at
http://www.pewforum.org/2014/04/04/global-religious-diversity/.
Here they are:
Explanation
The first graph is a pie chart.
- The individuals were, in theory at least, all humans on planet
Earth. [In practice, they must have done some sort of survey.]
- The random variable associated with these individuals was their
religious affiliation. This is a categorical RV.
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 random variable associated with these individuals was their
religious affiliation. This is a categorical RV.
Critique
Both graphical methods were reasonable: the RVs were categorical and the pie
chart showed percentages (adding to 100%) in each category.
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 about the quality of this data.
