The Mean and the Variance, or the Mode and Heterogeneity

A quick note.  A common refrain that we hear about this campaign season is how Trump’s supporters are angry blue collar whites and Sanders’ supporters are young liberals.  While they are no doubt true with regards to their modal base of support, i.e. their most common supporter, it is hardly likely that they are all that common.  I’ve been guestimating, based on rough extrapolations from exit polls that Sanders’ support is roughly 1/3 liberal, 1/3 young voters (probably larger, since the young and the liberal supporters of Sanders overlap quite a bit), and 1/3 blue collar whites who may not be especially young or liberal.  Trump seems to be drawing at least 1/2 his support from more conventional Republicans of all stripes, even if the blue collar working class whites seem to make up the biggest chunk of his supporters.

Many people mistake the average for the only.  This gets worse when we are speaking of modes for categorical data.  Even if, say, 45% of Trump’s supporters are made of working class whites, it leaves 55% who are not.


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