Test This

One of the refrains we’ve heard repeatedly during the Panicdemic (which is arguably worse than the pandemic) is: “We Need More Tests! We Need More Tests!”

There is a Chicken Little vibe to these calls for testing. A sense that people are running around like the sky is falling, and not thinking through the right testing strategy.

What are tests for? One is for diagnostic purposes in specific cases. To be frank, the value of such tests is minimal. There is no unique therapy for acute Wuhan Virus sufferers. The protocol is to treat the symptoms of acute respiratory distress the same way as one would treat such distress from other causes. So knowing that someone’s acute distress is caused by agent X as opposed to agent Y is of limited therapeutic value.

Insofar as identifying someone expressing symptoms would help identify others so exposed, a much more efficient strategy is to presume that the symptomatic individual is suffering from WV, track his/her contacts, and monitor and quarantine said individuals accordingly. Yes, there will be Type I (false positive) errors, but the cost of such errors is likely to be relatively small if an individual is suffering from an acute condition, regardless of the exact pathogen that caused it. That pathogen is obviously capable of causing severe problems, so why not isolate those exposed to it, even if you don’t know exactly what it is?

Another purpose of testing is to collect information about the prevalence, virulence, contagiousness, and fatality of the disease. Such information can be used to optimize the policy response.

Testing those who are symptomatic and/or have been exposed is exactly the wrong way to go about that. Such a testing strategy is rife with sample selection bias.

For weeks (mainly on Twitter) I advocated construction of a random panel data set. Select people at random. Test them, and test them at regular intervals–including those who tested negative. This would provide an unbiased sample that would permit more reasoned assessments and judgments about the nature of the pathogen. We could see how many people had contracted the virus, how many people they infected, the mortality rate (and how the mortality rate varied with age, health status, etc.), and the trajectory of the virus.

If that had been done, say, in January when shit started to get real in China, perhaps we could have been able to condition policy on better information. (Not to mention if the CCP had done that in, say, December, when it knew it had a problem on its hands–but decided to suppress information rather than suppress the pathogen.)

Why didn’t our Technocrats figure this out? Yeah. We should put more of our lives in their hands.

But that opportunity to get unbiased data has passed. Now we are forced to respond based on the most sketchy and biased data. Chicken Little proposals about testing will generate . . . more biased data. Which is arguably worse than useless.