Top 15 David Spiegelhalter Quotes

Randomised trials have proved the effectiveness of some Covid treatments and saved vast numbers of lives... also showing... overblown claims about treatments... as hydroxychloroquine and , were incorrect.

So far, these vaccines have shown themselves to be extraordinarily safe.

The most serious problem is anaphylactic reactions, and the advice is not to inject anyone with a previous history of allergic reactions to either a prior [vaccine] dose... or its ingredients.

In the UK, adverse reactions are reported using the “yellow card”... Up to 28 February, around 54,000 yellow cards have been reported... from... 10 million vaccinations... three to six reports per 1,000 jabs [0.3-0.6%]. That means a far greater number of side-effects are reported in the trials...

In the trials that led to the vaccines... adverse events were reported by 38% of those receiving the real vaccine... 28% of those who received the control [dummy, or fake vaccine, of which some were meningitis vaccine] also reported a side-effect. ...[F]ewer than 1% reported a serious adverse event, and of these... slightly more had received the dummy than the active vaccine. ...So there was no evidence of increased risk ...

(DVTs) [normally] happen to around one person per 1,000 each year... out of 5 million people getting vaccinated, we would expect... 5,000 DVTs a year, or... 100 every week. So it is not at all surprising that there have been 30 reports.

[W]hen... there have been 30 "thromboembolic events" after around 5m vaccinations, the crucial question... is: how many would be expected anyway, in the normal run..?

[S]omeone is diagnosed with autism after receiving the , so people assume a causal connection – even when there isn’t one.

It’s a common human tendency to attribute a causal effect between different events, even when there isn’t one present...

We need to think slow instead of fast, and resist drawing causal links between events where none may exist.

Framing is absolutely vital. ...All the work in communications is driven by the work of psychologists like Kahneman, Tversky...[etc.] The simplest one... is not always to talk about s, but to talk about s, and preferably... to give both. Our predict systems are almost always... positively framed, all in terms of survival. So we draw survival curves, not mortality curves... How long can you be without this condition. ...In a way you should give both, but ...it makes a big difference ...whether you talk about 2% mortality or 98% survival. ...2% mortality sounds rather terrifying while 98% survival sounds rather good, and we don't want to unnecessarily upset people... [W]e are all going to die ...It's 100% mortality in the end, but you want to show a decline in survival ...because it's just fairer and more likely to get people engaged rather than frighten them off immediately. ...[W]hen we ...provide an icon array that shows everybody, it shows the deaths ...patients like it. ...They like seeing out of 100 people ...in 10 years time, how many people are going to be alive ...because they have the chemotherapy now, or dead because of breast cancer...[etc.]

We find it very difficult to deal with... low numbers, one in a million, one in a billion... Once I have to start counting the zeros, all intuition and feeling goes. So it's hopeless, and of course we're bad at it. Why should we be good at doing that sort of thing? ...[I]t's more and more reported that people will use this expected frequency format, where instead of talking about... .03 per person year... What does that mean, for heaven's sakes. It's absolutely ridiculous scientific language for something. No, what you say is, out of 100 people... we would expect 3 for this to happen each year. ...You talk about a specific group of people, which you can... draw a... picture of... and that helps enormously. You... want to bring things to... whole numbers, small numbers, preferably between 1 and 100, or between 1 and 50... magnitudes that people have got a feeling for, and... no decimal places, no multiple zeros. You've got to get rid of all of that. You've got to get things to units people can understand, preferably on a scale of 1 to 10.

s are very valuable in... low probability, high impact events. Every time you cross the road there is a low probability and high impact that you're going to get run over. ...You take extra precautions to reduce... very small risk to... even smaller. ...[O]n an absolute risk scale, you [might] say, "Oh, I'm not going to bother... It's not worth doing..." but... by making that low risk even smaller, it's... valid... [P]eople discovered this... doing earthquake predictions... [T]he absolute risk... it's always low. They're very unpredictable... but telling people it's 10 times normal, or 100 times normal, people will act... appropriately. ...They won't panic. They won't rush away. ...[I]n Italy ...they ...sleep outside for a bit. ...So in certain circumstances relative risk can be very valuable... [U]sing both in... situations... with very small risks.., where... consequences are... severe... [and] the cost of the intervention, the action, is... minimal. Taking a bit more precautions, being a bit more careful... not putting a big investment into making a very small risk even smaller.... not walking under ladders... a low-cost change in your behavior to make a small risk even smaller... [A]bsolute risks really don't deal well with that, because you're talking 0.000...

s are disastrous. ...Relative risks are deeply misleading. They're a manipulative form of communication. To ever say, "Oh, this doubles your risk, or increases your risk 50%," absolute No-no! They are hopeless. In some situations they can be very valuable... but in general, medical things what... should be always given... s... with and without something... Like my s... I was getting... 15%, 10 year risk: 15 out 100 people like me might expect to have a heart attack or stroke. So I... roughly halved it... only in terms of relative risk... from 15% to 7-8%. ...Being told it halved it does sound good, but if wasn't a very big number in the first place, halving it is of no interest... especially if the thing's going to give me some side-effects... if it did, it would be completely pointless... [Y]ou cannot know... whether you should do something... [Y]ou cannot trade off the benefits... [and] the harms from a medical treatment without knowing the absolute risk. You cannot do it in any rational way whatsoever. ...A lot of the communication now is using absolute risk, which is a huge improvement.

We spent ages... working... for child heart surgery... such a delicate area, trying to find the wording for... random error or binomial variability... [Y]ou can give a percentage... 95% . Well, am I going to be one of the 5% or one of the 95%? We don't know. It's just chance or luck, fortune. We can't... use those words in... delicate situations... operating on children... Then we came up with a good phrase... which we used and tested on parents... It's "unforeseeable factors," not "unforeseen factors," because that would suggest someone's to blame... [T]he unforeseeable factors could lead some people to... not survive the operation, and some to survive. So... we can put you in a group, but we can't go beyond that... [O]nly what develops over time, in terms of complications, or something like that, could... put... you in one group or another. "Unforeseeable factors," I really like that phrase. I try to use it all the time, I recommend it.