Alternative Moscow Covid-19 Data Fit

  I may have mistakenly identified the Moscow Infected data column as new cases. Taken at face value the compartments appear to be related as follows.

Where S is the number of Susceptibles, I the numbet of Infected, D those who have Died and R the Recovered. The peak value of I appears to be a little farther off and so the value of I_max was included in the search to minimize the rms error.

The zero point in the plot above is somewhat uncertain due to fluctuations in the data.

Either way it looks like the people of Moscow will soon be switching to the downward sloping road to recovery.

Supplemental (May 24): There are different ways of reporting the spread of Covid-19, total number of cases to date, new cases for the day and the number of current active cases for example. This fit assumes Infected refers to the latter. One has to be on guard against making a mistake of this kind. The data can be corrupted if not everyone follows the same rules. The way one defines recovered can also  affect the counts. "Contrarians look" can be a source of problems.

Supplemental (May 24): It seems reasonable to refer to the curved line of the data fit as a trackline.

Supplemental (May 26): The curve could also be described as a tracing.