This is the text of an e-mail I sent to my local MP on Sunday:
Dear Ms Saxby
I was very concerned to read the following report on the BBC web site on Saturday morning:
“The south-west has always had relatively few cases – currently 778 infections a day, according to PHE. However, Dr Birrell says the north-west – 4,170 infections a day – is “more worrying”.” https://www.bbc.co.uk/news/health-52944037
The latest summary report from PHE which covers the period 20 January 2020 to 3 June 2020 shows a cumulative total number of cases of 11,945 for the South West and 37,321 for the North West. (National COVID-19 weekly summary report: 4 June 2020 – accessed from https://www.gov.uk/government/publications/national-covid-19-surveillance-reports)
The latest figures on the Coronavirus Data Dashboard (https://coronavirus.data.gov.uk/ – accessed on 6 June 2020) show a cumulative total of positive test results of 7,818 for the South West and 26,133 for the North West. The granular case data downloaded from this site shows a total of 1,264 positive tests for May – an average of 41 a day. For the North West, the figures are 5,267 with an average of 170 a day. North Devon has had 92 positive cases since the pandemic began. With only 13 cases in the whole of May and no positive tests since 23 May.
In all cases the regions cover the same geographic area (and in the case of the South West this includes Bristol, Gloucestershire, Wiltshire and Dorset!).
There is a massive mismatch between the figures quoted in the BBC article which are reported as having come from PHE, those in the PHE report and those from the government’s Coronavirus data web site.
Of course, the number of cases that test positive is lower than the true number of infections. However, is there really almost a ten-fold difference in the South West and 25-fold difference in the North West?
I can fully accept small differences in the data because of delays in test results being received etc but not differences of this magnitude.
What is going on here? Why don’t the figures match?