# COVID-19 NZ: Using a Fibonacci sequence to estimate total case numbers IV

We continue the work done in previous posts to estimate (Re**=2) the (final) total number of cases. See:
https://aaamazingphoenix.wordpress.com/tag/fibonacci/

We noticed in the most recent case that the Fibonacci sequence crossed the actual cumulative case data very close to the midpoint.

We conjecture that this crossover point may be used to estimate the (final) total number of cases.

The closest crossover point was 604 on Day 32 (30 March) with the next value on Day 33 (31 March) being 800 cases using Re2**=2.

Adding these two numbers together gives 1404 for the total number of cases.

We create an S-Curve (c.f. logistic curve) by flipping and adding on the previous values for the Fibonacci estimated daily number of cases. We could also have flipped the actual number of cases instead as we did for China (using values for the next two dates). See the last two graphs at the bottom of this post.

This gives the following graph (Re**=2):

The current number of cases in New Zealand is 1487 (for 4 May) with no new cases and no new deaths yesterday.

The curve (Re**=2) estimates 1400 cases on 17 April (Day 50) very close to the 1409 actual cases recorded on that day and even closer to the 1401 recorded for the previous day.

Note: the curve Re**=2 is created from the curve Re*=2, using as the midpoint where the curve crosses the actual number of (cumulative) cases.

The estimated final total (lower end of the range) in a previous post for the final number of COVID-19 cases was 1350 (or 1355) and once 10% was added on this gave 1485 (1350+135), very close to the current number of cases (1487). Recall we rounded the 1485 up to 1500 in the previous post.

As previously mentioned it is recommended that 10% is added on to case estimates to allow for a long tail.

This gives an estimated range of 1400-1540 cases. The midpoint of this range is 1470, reasonably close to the actual number of cases presently (1487).

We conjecture that the above method may be useful in estimating case numbers for other countries.

Below is the table of data for the graph:

 Date Day# Re=2 Cases Re*=2 Re**=2 7/03/20 9 5 8/03/20 10 5 9/03/20 11 5 10/03/20 12 5 11/03/20 13 5 5 4 4 12/03/20 14 6 5 4 4 13/03/20 15 6 5 4 4 14/03/20 16 11 6 8 8 15/03/20 17 12 8 8 8 16/03/20 18 17 8 12 12 17/03/20 19 23 12 16 16 18/03/20 20 29 20 20 20 19/03/20 21 40 28 28 28 20/03/20 22 52 39 36 36 21/03/20 23 69 52 48 48 22/03/20 24 92 66 64 64 23/03/20 25 121 102 84 84 24/03/20 26 161 155 112 112 25/03/20 27 213 205 148 148 26/03/20 28 282 283 196 196 27/03/20 29 374 368 260 260 28/03/20 30 495 451 344 344 29/03/20 31 656 514 456 456 30/03/20 32 869 589 604 604 31/03/20 33 1151 647 800 800 1/04/20 34 1525 708 1060 948 2/04/20 35 1899 797 1320 1060 3/04/20 36 2181 868 1516 1144 4/04/20 37 2394 950 1664 1208 5/04/20 38 2555 1039 1776 1256 6/04/20 39 2676 1106 1860 1292 7/04/20 40 2768 1160 1924 1320 8/04/20 41 2837 1210 1972 1340 9/04/20 42 2889 1239 2008 1356 10/04/20 43 2929 1283 2036 1368 11/04/20 44 2958 1312 2056 1376 12/04/20 45 2981 1330 2072 1384 13/04/20 46 2998 1349 2084 1388 14/04/20 47 3010 1366 2092 1392 15/04/20 48 3021 1386 2100 1396 16/04/20 49 3027 1401 2104 1396 17/04/20 50 3033 1409 2108 1400 18/04/20 51 3038 1422 2112 1400 19/04/20 52 3039 1431 2112 20/04/20 53 3044 1440 2116 21/04/20 54 3044 1445 2116

The two graphs below show the results for flipping the actual number of Cases (see the light blue graphs CASESF and CASESF1). The latter graph flips the number of cases one day later.

Below are enlarged versions of the two graphs above:

My other COVID-19 posts can be found here:
https://aaamazingphoenix.wordpress.com/tag/coronavirus/

Data for my posts can be found at:
https://www.worldometers.info/coronavirus/
https://en.wikipedia.org/wiki/2020_coronavirus_pandemic_in_New_Zealand

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https://guestdailyposts.wordpress.com/guest-pingbacks/