Attention Conservation Notice: I use a recent study about COVID-19 as an excuse to demo an R package I am developing. Some other reasons not to read this: (a) I am not an epidemiologist and (b) I do not plan to explain confidence functions enough for the uninitiated to make sense of this post. Andrew Gelman had an interesting post recently about the DANMASK-19 trial out of Denmark. This study randomized individuals to recieve a mask recommendation and a supply of 50 surgical masks (or not):