The head of the UK Statistics Authority has accused the government of continuing to mislead the public over the numbers of tests carried out for Covid-19.
“The aim seems to be to show the largest possible number of tests, even at the expense of understanding,” said Sir David Norgrove in a letter to the health secretary, Matt Hancock.
He upbraids the government for mixing up tests carried out with testing kits sent out by post. “This distinction is too often elided during the presentation at the daily press conference, where the relevant figure may misleadingly be described simply as the number of tests carried out. There are no data on how many of the tests posted out are in fact then successfully completed,” he says in his letter.
Norgrove has a number of other criticisms of the way testing is carried out and the data presented to the public. His letter is a second attempt to get more clarification from the government.
On 11 May, he asked for more detail of the plans for 200,000 tests to be carried out in England every day. It should be clear whether the target referred to testing capacity, the tests that have been administered, the test results received or the number of people tested, he wrote.
Hancock replied, welcoming Norgrove’s comments, saying he was publishing details of how the 200,000 tests would be counted. “The programme is committed to being as transparent as possible about its work,” said Hancock.
Dido Harding, who had taken over its leadership, “is keen to engage with you on how we ensure the right statistical reporting of the test and trace programme as it develops”, he wrote.
But Norgrove’s latest letter to the health secretary makes clear that his doubts have not been allayed.
Statistics on testing serve two purposes, he writes. “The first is to help us understand the epidemic, alongside the ONS survey, showing us how many people are infected, or not, and their relevant characteristics.
“The second purpose is to help manage the test programme, to ensure there are enough tests, that they are carried out or sent where they are needed and that they are being used as effectively as possible. The data should tell the public how effectively the testing programme is being managed.
“The way the data are analysed and presented currently gives them limited value for the first purpose. The aim seems to be to show the largest possible number of tests, even at the expense of understanding. It is also hard to believe the statistics work to support the testing programme itself. The statistics and analysis serve neither purpose well.”
As well as the confusion between tests carried out and tests posted, Norgrove says it is not clear from the data how often people are tested twice. He objects that the data is presented in a way that is hard to understand. “Many of the key numbers make little sense without recourse to the technical notes, which are themselves sometimes hard to follow,” he writes.
On Monday, the Department of Health and Social Care tweeted that so far 4,484,340 tests had been carried out, with 128,437 tests done on Sunday 31 May – well short of the 200,000 ambition. A total of 276,332 people have tested positive.