Never Trust a Clean Partisan Story



Before [wrong]:

After [correct]:


The biggest problem with this study is the fact that they made what is an elementary statistics error and it went all the way to publication and no one caught it.

The authors took the per capita COVID case and death numbers among the “red states” and “blue states” and ran an analysis on them. In doing this, they gave North Dakota the same weight as Texas and Hawaii the same weight as New York despite the obvious population differences. Their chart is tiny and unreadable, so I’ve roughly duplicated their work here.

At first glance, this looks like the authors at least have their data correct. It looks like, after the initial wave, states with red governors had consistently higher patterns of cases and deaths from the summer all the way through the winter surge.

However, what we’re seeing here is due to the fact that the authors weighted the death rates for small and rural states with the same weight that they applied to high population states. This is a statistics error that is so common it has its own name: Simpson’s Paradox. It is when you take the average of the averages instead of calculating the overall average based on the properly weighted data.

Author(s): PoliMath

Publication Date: 13 May 2021

Publication Site: Marginally Compelling at substack