Mar 26, 2020

Kevin Duffy on the coronavirus, experts, simple narratives and statistics

Beware the following:

1. Self-appointed "experts" provide a simple explanation to a complex problem.

2. Their message gets promoted by non-objective authorities (more "experts") like politicians and the mainstream media who have their own biases and agendas.

3. The crowd swallows this simple explanation whole and repeats over and over until it becomes accepted truth.

This explains the reaction to the coronavirus warnings to a "t."

"Experts" like CDC and WHO said Covid-19 could infect 40-70% of the population and that the average mortality rate is 3.4%.  True, but not true...

The average case mortality rate is 3.4% (U.S. so far is 1.5%).  This is not the overall mortality rate because the denominator only counts confirmed cases.  (This does not include everyone who caught the virus, but was asymptomatic or never got tested and reported it to the authorities.)

People are freaked out because 3.4% sounds a lot scarier than the 0.1% mortality rate from the seasonal flu. However, the flu rate is based on estimated cases.  If we look at confirmed cases, the case mortality rate from the seasonal flu is more like 10%.

Now I'm not suggesting the seasonal flu is 3x as deadly as Covid-19.  I'm only suggesting that Covid-19 is nowhere near 34x as deadly as the flu.  To multiply 40-70% by a 3.4% mortality rate is to make an obvious and gross statistical error.  This would imply between 4.5 mil and 7.8 mil deaths in the U.S.  No wonder people freaked out!

How could everyone miss something this obvious?  That is the nature of crowds... and blindly following "experts."

Does anyone remember the Beardstown Ladies who wrote three bestselling investment books during the mid- to late-'90s?  They became minor celebrities for beating the stock market for an 11 year period, doubling the S&P 500's annualized return.  As it turned out, they miscalculated their performance (honest mistake). In fact, they underperformed the market by 3% per year.  This gross error wasn't caught for three years!

~ Kevin Duffy, Facebook post, March 26, 2020

Image result for beardstown ladies

No comments: