when you’ve got really steep differences between subpopulations and the subpopulations are of very different sizes, the overall population average will be very different from simply looking at the average of the two populations.
– The base risk rates for each group are extremely different (3.9 per 100K for young, and 91.9 per 100K for old)
– The percentage each subpopulation makes up in the larger population is very different (67% young, 33% old)
– The vaccination rates are very different by population (76% young, 92% old)
Author(s): Mary Pat Campbell
Publication Date: 19 August 2021
Publication Site: STUMP at substack