Some people asked me for the official definition of vaccine efficacy (or VE as it is usually abbreviated). As I suspect you might be thinking, it’s a fraction expressed as a percent. For example, suppose you had 300 cases in the unvaccinated group and 100 cases in the vaccinated group. The VE is then gotten … Read more
Fauci is a great virologist, but he doesn’t seem to (automatically) do a back of envelope calculation before throwing out a statement. And so one of his most recent statements (on voting), doesn’t pass the smell test. So what happened? Fauci said this week there is “no reason” Americans can’t vote in person for the … Read more
Some people asked me how the mathematics of vaccine testing works. So, because vaccine trials are actually a bit different than a traditional drug trial, and the popular press isn’t really clear on how they work (to put it mildly), I thought I would explain, in quite general terms how they work. Unfortunately, the mathematics … Read more
https://jamanetwork.com/journals/jamacardiology/fullarticle/2768916 Yes I know this isn’t math – but it just confirms that people need to do everything possible to not get this horrible, horrible disease, i.e. (re)read my post https://garycornell.com/2020/04/21/multiplication-of-probabilities-or-what-to-do-when-you-have-to-go-shopping/. (HT to Charlie Stross.)
It’s hard to present data in an insightful way. I always recommend that people check out the works of the statistician (and artist!) Edward Tufte (https://www.edwardtufte.com/tufte/) to learn more about how to do it. Graphs can be especially problematic because of how easily they can be used to mislead – even with no intention of … Read more
Remember syllogisms? You know: All men are mortal Socrates is a man Therefore Socrates is mortal While this kind of reasoning dominated logic for 2,000 years, it is too limiting and modern (mathematical) logic goes far beyond these methods of reasoning. But hey they still work and are worth trotting out from time to time … Read more
Derek Lowe has his take on them and I was pleased to see that I basically got it right. https://blogs.sciencemag.org/pipeline/archives/2020/07/20/new-data-on-the-cansino-vaccine https://blogs.sciencemag.org/pipeline/archives/2020/07/20/new-data-on-the-oxford-az-vaccine Next, Wired has a very good article on the need to inject some realism into the discussion by the mainstream media about the vaccines. As they point out, yes we should be encouraged, but … Read more
Oxford published the (combined) Phase 1/2 results of their modified Chimpanzee adenovirus vaccine and they were very very good (https://www.thelancet.com/lancet/article/s0140-6736(20)31604-4). As I mentioned in a previous blog, the technology used by the Oxford vaccine candidate (a modified Chimpanzee cold virus) has a much longer track record than the mRNA vaccine candidates such as the one … Read more
Whenever you look at a graph there is a tendency to see trends. Then you extrapolate into the future by extending the curve. To a mathematician this practice is extremely suspect. For example look at the following curve: What is going to happen next? Well your guess is as good as mine! But as a … Read more
The math is easy, the assumption on what percentage of the population you need to be immune to get to herd immunity is the issue: The usual estimates for herd immunity say that for Covid 19, you need about 60-70%% of people to be immune before herd immunity kicks in. The first generation of vaccines … Read more