COVID Odyssey: Winter Warning NZ 8 ~ 2021 Delta midpoint ~ Are we there yet?

We hope we are near the midpoint for the current COVID-19 outbreak (Delta variant) in New Zealand.

We had around 82 cases yesterday (29 August) and the previous day.

We hope that the number of new cases will start to decline very soon and that there will only be one peak. In the original 2020 outbreak, the the case numbers were bimodal (had two peaks).

We will not know for several days.

We estimate the number of Cases (C) using the formula

C(d) = 1.16 x SQRT(2)^d

where ^ means ‘to the power of’ and

d is the number of days from 10 August 2021.

We modify this formula below and obtain estimates up to Wednesday 1 September:


Below is the PDF version which may be clearer:


Starting Day 16 (d = 16), 26 August, we scale the cases numbers by a factor f (a function f) which is also an exponential function.

Our estimate for the number of cases becomes (starting with d = 16) becomes

C(d) = f(d) x 1.16 x SQRT(2)^d


f(d) = .9328  x 0.88^(d-16)

[originally we used 0.8858 instead of 0.88]

A graph of the estimated case numbers (and actual case numbers) is below:




Also see:

COVID Odyssey: Winter Warning NZ 9 ~ C = ar^d ~ A trivial way to estimate total case numbers

COVID Odyssey: Winter Warning NZ 7 ~ Will we have 100 cases today? ~ 1000 total by Wednesday?

COVID Odyssey: Winter Warning NZ 5 ~ Estimating the number of 2021 Cases ~ Where will the midpoint be?

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