Julien Riou writes: Stan epidemiologist here. We actually just released a preprint [estimating death rates of people infected with coronavirus, breaking down the population by age and then poststratifying] using Stan (https://www.medrxiv.org/content/10.1101/2020.03.04.20031104v1). Crude estimates of case fatality ratio obtained by dividing observed deaths by observed cases are biased in two ways: 1) Deaths are underestimated …