Originally Posted by
FlareArmed2
So we can see that in the early stages the number of cases increased at about 50% per day, or more than doubled every two days. From about 28 Jan the rate decreased to about 25%. Recently the rate of increase has dropped even further. Conclusion: the rate of increase is no longer exponential but is moving towards a null rate of increase.
While this might be a good sign - of course even if the daily increase in the number of cases has dropped to 25% this is still not a LINEAR function. A LINEAR function would be Cumulative Number of Cases = Some Constant x Number of Days Since Start of Outbreak.
Any quantity that grows by a fixed percentage at regular time intervals exhibits EXPONENTIAL growth - in the form y = a(1 + r)^x
E.g. Cumulative Number of Cases = Starting Number of Cases x (1 + Growth Rate) ^ Number of Days Since Start of Time Period
This doesn't map on to public understanding of the term "exponential" when the growth rate is low - but nevertheless it is.
So for 25% daily growth you've got...
Cumulative Number of Cases = Starting Number of Cases x (1 + 0.25) ^ Number of Days Since Start of Time Period