In BC we've learned that we need to distinguish between the positivity rate for "testing due to symptoms or known exposure" and "testing for screening" (e.g. the film industry tests all their crew daily). The former positivity rate is much higher, but the latter may be more useful as a long-term trendline to follow.

I could get behind that. Hopefully we learn to make that distinction without enduring too much in the way of suffering.

Test positivity is a weird metric because of things like this. It's interesting week-over-week, but loses meaning over the long term as testing protocols, other behavior changes, and changes to the disease. This makes it a lousy metric for policy making.

There was a county in Louisiana that went back into a shutdown Thanksgiving week, when nothing at all had changed, except that a local university was on break and had stopped flooding the daily statistics with thousands of negative tests.

Not to mention the perverse incentive: if you feel sick, you want to avoid getting tested and counted as a positive if you don't want your locality or employer to shut down. There is a theory that this accounts for much of Japan's perceived success - antibody studies show just as much prevalence as everywhere else, what happened was that all the mild cases never got tested.

> Not to mention the perverse incentive

There are also non-perverse incentives. If I feel sick and live alone, a test test result doesn't give me much actionable information, takes time, and puts the people giving the tests at slightly more risk.

Especially true for those of us who live in an apartment, where getting a test would mean coughing our way through the hallways.