The Lifeboat News
[ Message Archive | The Lifeboat News ]

    Re: I'm a fan of Bayesian statistics - better than standard statistics for clinical trials...probably Archived Message

    Posted by Rich on October 12, 2020, 2:36 pm, in reply to "I'm a fan of Bayesian statistics - better than standard statistics for clinical trials...probably"

    It's ironic that you should fairly castigate GSK and pharma in other posts and then use an article by someone who uses his position in the pharmaceutical industry as a call to authority.

    It was because of his position as a former Vice President and Chief Science Officer for Pfizer that I was interested in the first place. That someone in a position like that would come out and say that 90% of the tests were giving false poitives and that the government were lying about them. Anyone who’s worked for decades for Big Pharma with their horrifying record as an industry is bound to be considered suspect but it doesn’t automatically make all of them biased liars all of the time. For example Craig Murray was quite happy at the FCO until he found out about UK involvement in torture in Uzbekistan. (I’m not saying that Yeadon is in any way comparable with CM BTW).

    This article is notable for its omissions. He must know that he's missed half of the Bayes position out. Reminds me of Pinter's description of writers who lie. They stop being writers and become politicians.

    For anyone who thinks this article usefully takes down testing.

    All tests have false positives and negatives. Briefly, Bayes says that the probability of a result being false depends not just on the reliability of the test itself but also on the conditions of the experiment, so for a situation in which there are genuinely no positive cases, any positive test must be a false positive. What's missing from the article is the corollary - in a situation where all the tested are genuinely positive then the chances of a false positive are zero.

    For a test with a 1% false positive rate when 10,000 people without the disease are tested then 100 will be positive. This rate is constant so if the number of tests being performed stays the same, and there is no covid, then the number of (falsley) positive tests should also remain static..... or should increase proportionally with increased number of tests.

    Yes, I get all of that but I’d totally missed the absent corollary aspect – thanks for pointing it out.

    The government has stopped publishing the number of daily tests so it's not possible to know the denominator. There is weekly data which suggests that the testing capacity has increased by 40% since August. The number of positive tests has increased many times more than this.

    I find it highly suspicious that they’re no longer publishing the data and how reliable is the 40% I wonder? The question remains how many false positives really are there?

    As we are seeing more admissions with respiratory failure I'm sure the proportion of false positives is going down.

    Where is the science for the so called second wave?

    He also assumes that the people being tested over the summer had the same low incidence as the whole population. Given how hard it was to get a test in the last few months I would assume that it was people with viral symptoms who got tested and had a higher incidence of covid the general population. Therefore his assertion that the pre test probability is low is also an assumption requiring proof.

    Maybe but there are various reasons why people would want to be tested. Some are being tested in the hope of a negative test to avoid the two week quarantine for example. Even if people were having difficulty getting a test it would be easy to lie about having symptoms in order to get one. I agree that his assertion requires proof.

    Bayes is a bit mind boggling, so no surprise that the article is bamboozling but this guy from the pharma industry is lying by omission. I don't know what the incidence is, or will be. Without transparent testing and data publication which includes the number of tests being performed, it's still not possible to know where we are. To claim that that invalidates a standard medical test is flam.

    I agree with you that someone in his position would almost certainly know about the corollary etc but I don’t get why he’d lie Dan – what’s in it for him? Why would he pick a fight with the government if his evidence can be so easily exposed? He’s publicly challenged Hancock on the issue.

    Cheers Dan and thanks for taking the time.

    Cheers,
    dan

    Message Thread: