(1/8) Germany's #COVID19 death rate is rising. Where will it stop? Here's a suggestion. Case fatality rate (CFR) is calculated dividing number of deaths by number of confirmed cases. That's not the chance of an infected person to die, since many infections probably go unrecorded.

(2/8) In Germany, with treatment and testing consistent from early on and healthcare system functional, I'd expect a relatively stable CFR. Why is it rising? Maybe CFR is rising because we ignore the time difference between diagnosis and death.

(3/8) Today's deaths were counted as cases some time ago. Wouldn't a more accurate CFR compare today's deaths with cases X days ago, so numbers correspond to the same group of people? Here I divided total deaths of every day by total cases 5 days before it:

(4/8) CFR on 23.3 is now significantly higher: 1% and not 0.4%. This is because number of deaths that day (123), which was previously divided by number of cases on the same day (29,056), was now divided by the number of cases 5 days before (12,327) – a much smaller number.

(5/8) The line also flattened a bit. Now let's check a 2 weeks offset. CFR on 23.3 tops 10%- this is surely exaggerated: we divided the deaths by cases of a date so early, that total cases were too low and resulted in an unrealistic rate. These dates don't seem to correspond.

(6/8) What's the right offset then? Given a person who died today- when on average were they tested and counted as a confirmed case? If we assume that there is a consistent German CFR, could we find the right offset by looking for the one that creates a somewhat stable CFR?

(7/8) Here are a few candidates. It seems like somewhere between 10 and 11-days offset, but closer to 10, CFR looks more or less stable throughout the period:

(8/8) Moreover, the variation of rates at a 10-days offset is the narrowest of all: 0.65% between lowest and highest, 3.25% and 3.9% respectively. Will 3.6%, the mean CFR at this offset, be Germany's final rate?