Thursday, March 19, 2020

The importance of what we don't know …

… In the coronavirus pandemic, we're making decisions without reliable data. (Hat tip, Dave Lull.)

Projecting the Diamond Princess mortality rate onto the age structure of the U.S. population, the death rate among people infected with Covid-19 would be 0.125%. But since this estimate is based on extremely thin data — there were just seven deaths among the 700 infected passengers and crew — the real death rate could stretch from five times lower (0.025%) to five times higher (0.625%). It is also possible that some of the passengers who were infected might die later, and that tourists may have different frequencies of chronic diseases — a risk factor for worse outcomes with SARS-CoV-2 infection — than the general population. Adding these extra sources of uncertainty, reasonable estimates for the case fatality ratio in the general U.S. population vary from 0.05% to 1%.

Remember those known unknowns and unknown unknowns of some years back? I don't think many people study epistemology these days.


  1. This topic is also covered here: This blood test can tell us how widespread coronavirus really is. In the mean time, epidemiologists have been tracking data from other countries, as it has to do with known virus spreading as well as that of the new Covid-19, to come up with such statistics that show that Covid-19 is what some Z-Generation kids want to call a Boomer Remover. What's also being studied is whether suppression or mitigation is best for flattening the curve. As we find out now that Italy's deaths have surpassed China's, what we do not know, and are trying to model is how such a virus would spread in the USA, each country having its peculiarities, such as urban crowds versus rural distancing, health care access, travel habits, and the different approaches the governments take or are late in taking, even state to state and city to city.

  2. Well, as I have said, I am in favor of taking all reasonable precautions. What I am not in favor of is encouraging panic.