Day: 11 June 2020

By Sue Denim After Toby published my first and second pieces, Imperial College London (ICL) produced two responses. In this article I will study them. I've also written an appendix that provides some notes on the C programming language to address some common confusions observed amongst modellers, which Toby will publish tomorrow. Attempted replication. On the June 1st ICL published a press release on its website stating that Stephen Eglen, an academic at Cambridge, was able to reproduce the numbers in ICL's influential Report 9. I was quite interested to see how that was achieved. As a reminder, Imperial College's Report 9 modelling drove lockdown in many countries. Unfortunately, this press release continues ICL's rather worrying practice of making misleading statements about its work. The headline is "Codecheck confirms reproducibility of COVID-19 model results", and the article highlights this quote: I was able to reproduce the results… from Report 9. This is an unambiguous statement. However, the press release quotes the report as saying: “Small variations (mostly under 5%) in the numbers were observed between Report 9 and our runs.” This is an odd definition of "replicate" for the output of a computer program, but it doesn't really matter because what ICL doesn't mention is this: the very next sentence of Eglen's report says: I observed 3 significant differences:1. Table ...

Yesterday, Professor Neil Ferguson told the Science and Technology Select Committee in the House of Commons that if the Government had locked down a week earlier, the death toll would be less than half what it is now. The epidemic was doubling every three to four days before lockdown interventions were introduced.So, had we introduced lockdown measures a week earlier, we would have reduced the final death toll by at least a half. But where's the evidence that the number of people becoming infected was "doubling every three to four days" in the week running up to lockdown? Numerous analyses – the latest by Simon Wood, a Professor at Bristol University, entitled "Did COVID-19 infections decline before UK lockdown?" – suggest the R number was <1 before the lockdown was imposed. Here's one of Professor Wood's graphs, showing the daily infection rate in the lead up to and immediately after lockdown (the red line). Inferred daily infection rate for England and Wales. Light grey and dark grey regions show 95% and 68% confidence regions, respectively. You can read more about Professor Wood's paper in this blog post by Fraser Nelson. The same conclusion was reached by Carl Heneghan, Professor of Evidence-Based Medicine at Oxford, who has long maintained that infections peaked shortly after the Government introduced a raft of social ...