[ACow_Adonis]

So this comes back to my statement about proper equipment and proper thresholds.

obviously 37 practically isn't a fever, and 32 is ridiculous.

But let's accept it on face value, so it gave you a false positive, which caused you to pause for a second reading, and then a true negative (well, unless you count the 32 as a false positive for hypothermia) and you went in.

That temp checks create false readings isn't really news: for me the question is so they create statistically significantly better outcomes. As a statistics guy, my head says they do. The objections I hear to them sound to me like the objections to bmi: that it's not universally perfect is not reason to dismiss it. This seems to me like the perfect being the enemy of the good enough.

[ramraj07]

You called yourself a stats guy so I’m going to push, can you show any rigorous analysis by anyone suggesting that theres any benefit to doing temp checks? Is there any number anywhere that gives false positive rate estimates for typically used temperature checking methods? Or false negatives?

[btilly]

Here is a back of the envelope.

First of all, the important thing is the R number - how many people does the average infected person infect. If that is above 1, you get spread. Below 1, it dies out. Without mitigations, R is estimated at about 3. With mitigations, the UK is posting various numbers in the 0.7-1.0 range. (See https://www.bbc.com/news/health-52473523 for a source.) Let's assume that the USA is similar.

The question to ask is this. Do the temperature checks make the difference between being above or below 1.0?

Per https://www.webmd.com/lung/news/20210110/59-percent-of-covid... about 60% of spread comes from people who are asymptomatic. So about 40% happens from people who are symptomatic. Per https://www.healthline.com/health-news/what-is-the-risk-of-g... about 55% of spread happens at stores. If those factors were independent, about 1/4 of the spread would happen from symptomatic people at stores. If the temperature checks avoid a significant fraction of those, then in the real world it may indeed be the difference between pandemic spread and dying off.