Covid-19: Chief statistician criticises government over reporting of testing

The chair of the UK Statistics Authority has said that recent limited changes to how the government presents its official data on covid-19 tests, although welcome, mean that the figures are “still far from complete and comprehensible.”

In a letter to the health secretary Matt Hancock, David Norgrove said that the way the data are analysed and presented currently “gives them limited value” to help scientists understand the epidemic and extract basic trends. “The aim seems to be to show the largest possible number of tests, even at the expense of understanding,” he wrote on 2 June.1

On 11 May Norgrove wrote to Hancock urging the government to make its data on the national covid-19 testing strategy clearer.2 Hancock responded in a letter sent on 27 May that developments to improve data reporting were already under way.3

Norgrove criticised the way that the headline total of tests reported at the daily press conference adds together tests carried out with tests posted out. There are no data on how many of the tests posted out are, in fact, then successfully completed.

The notes to the daily slides presented at the press conference say that some people may be tested more than once. Norgrove pointed out, however, that it is not clear from the published data how often this is the case.

Norgrove called for test results to include data on key types of employment—for example how many are medical staff and care staff. Data on age, sex, and location should also be published.

The letter also called on the government to develop and publish key metrics for the test and trace programme to avoid the situation that has risen in relation to the testing programme. The statistics must be readily understood by the public through, for example, population adjusted maps of hotspots, he writes.

Norgrove said that “the testing statistics still fall well short” of the code of practice for statistics. “It is not surprising that, given their inadequacy, data on testing are so widely criticised and often mistrusted.”