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Those Coronavirus Maps Would Tell Us More If They Were Color-Coded on a Per Capita Basis


Here on Blue Virginia, each day, we get to see a map of Virginia, where I live, that’s color-coded on the same basis. The dark areas are in the Virginia suburbs of Washington, D.C., and in the Richmond area. My own rural county in the west — Shenandoah County — is a lighter color.

And every night, on MSNBC, we can see color-coded maps in which the states are darker or lighter depending on whether they have more or fewer identified cases of the virus. New York is darkest. California a a bunch of other states are the next level down in terms of their darkness. The mid-section of the nation is mostly light in color.

Those maps have some information value. But they would be a good deal more informative if they were keyed not to simple number of cases, but rather to the proportion of the population that carries the virus.

If the virus were equally distributed throughout the population — i.e. if in every location the same percentage of the population were infected — the current way of color-coding the map would be quite similar to these maps we see. Fairfax County would have more cases than Shenandoah County. And New York and California would have a lot more cases than Wyoming and Alaska. In each case, the more populous areas would be darker, even though they wouldn’t be harder hit.

But, it might be said, people die on a per capita basis. So we want to know, How prevalent is the threat? How likely is a random person I encounter to be infected?

For that reason, I think the more useful information — both in the state-by-state maps, and in the county-by-county maps — would be coded to show where a greater and where a lesser proportion of the population is infected.

In particular, I’ve been wanting to see whether those states whose governors refused (or were slow to) put shelter-in-place orders into effect were suffering the predicted consequences of not following the advice of the experts. But geographically large states with relatively small populations — like Nebraska, the Dakotas, Wyoming, etc. — won’t have large numbers of cases even if they are turning into “hot spots.”

And I’ve wanted to be able to see from the color-coded maps how much the infection rate in the rural areas (i.e. the less populous) is rising.

So I wish they’d change these color-coded maps to show the proportion of the population infected, and not confound that information so thoroughly with the variables of total population and population density.