In recent years, under the influence of statisticians, the medical profession has dialed back on screening tests.  With relatively rare conditions, widespread testing yields many false positives and doctor visits, whose collective cost can outweigh benefits.  Coronavirus advice follows this line – testing is limited to the truly ill (this is also due to a shortage of test kits). Alan Blinder, former Fed vice-chair, argues for a much more aggressive testing program, from an economic standpoint.  Until most people know, or have confidence that they can readily find out, whether they (or their family and co-workers) have Covid-19, any part of the economy that relies on physical interaction will continue to grind to a halt.  Neeraj Sood, in yesterday’s Wall Street Journal, points out that we don’t really know how Covid-19 mortality compares to the flu, and argues not only for more testing, but for testing of random subjects, to avoid selection bias and gain a better idea of the disease’s prevalence.  He feels that, until we have a good idea of the disease’s true mortality rate, panic and worst-case scenarios will prevail.