On 27th April, I posted some short-run projections of COVID-19 cases and deaths. The plots below show how the daily new cases per million population and deaths per million population compare with reality (at least the confirmed case rates and death rates up to 4th May according to Johns Hopkins CSSEGIS Data.
Its a mixed bag. The projections match reasonably well for a few countries and are very different for others. I’ve revised the smoothing algorithm I used, and that may result in improved projections. But overall, I think I’m not doing much better than IHME, and should probably leave it to those with better models that use SEIR (susceptible-exposed-infected-recovered modeling) or computer simulations of case transmission.
Vox recently published an excellent article on the problems with the IHME modelling of COVID-19. The article also gives a link to a site which has been set up so that you can look at the US predictions made by old versions of the IHME model (and another model). The IHME models are frequently fairly far off. Here is the comparison for the USA as a whole (you can also examine State specific projections).
Its clear that the projection method takes the latest data point and plummets and essentially the same rate as the earlier rise. On second thoughts, I think my short-run projections are doing better than these for many countries.