Dr John Briffa is involved in an interesting discussion on his blog. In a response to a comment I made that included a link to MMR – The Facts he wrote “In the link you supplied under ‘How do we know that MMR is safe?’, we are informed that…” and went on to paste several bullet points. Which weren’t on the page I’d linked to. This is the page: http://www.mmrthefacts.nhs.uk/library/sideeffects.php and it contains data on the number of children suffering from the effects of contracting measles compared with the number of children suffering from the side-effects of the MMR vaccine. Having quoted from a different page than the one I had linked to, Briffa then used this quote to back up this statement:
The first three bullet points tell us how widely and for how long it has been used (this is no different from saying ‘billions of people have crossed roads over the past 50 years’ – it tells us NOTHING AT ALL about safety – NOTHING).
True – the first three bullet points he copied and pasted told us nothing about safety. The page I actually linked to, however, did tell us something about safety and it used scientific evidence to do so. To paste information from a different link to the one I was using to demonstrate my point is fundamentally dishonest and I think it tells us something about the way Briffa argues. I’m not the only person who has picked up on Briffa constructing ‘straw men’ – here is another example. Here’s more of Briffa’s responses to my comments:
You’re right, the arbitrary nature of p-values is not a ‘secret’, but you’d be surprised just how much this fact is not fully understood or appreciated by those with no scientific training (like the majority of the readers of my site, I suspect). So, nothing wrong with pointing that out, I reckon.
Fair enough. He hasn’t explained p-values though. If his readers don’t fully understand or appreciate the arbitrary nature of p-values then perhaps they won’t fully understand or appreciate p-values themselves. If Dr Briffa is going to educate his readership perhaps it would be better to do a more thorough job and explain what p-values are before he tells people that they are arbitrary (which, apparently, therefore means scientific findings are arbitrary).
What I think happens in the real world is that when a scientific study pronounces a finding that is said to be ‘statistically significant’ or not, is that people interpret that to mean that a drug works or doesn’t or a vaccine is safe or not. And what I’m saying (if this wasn’t absolutely clear in the post) is it’s not like that: because the cut-off for what we determine to be ‘significant’ is arbitrarily set. This may be obvious to you. But as I pointed out above, I actually don’t think it’s obvious to everyone.
If people interpreted statistically significant scientific findings as showing that a drug worked relatively well or that a vaccine was relatively safe then I think they would probably be right to do so. Missing out the word ‘relatively’ and making safety and efficacy absolutes makes a big difference, and I don’t think that p-values being arbitrary is that important a factor in this – scientific evidence would be nuanced and safety and efficacy relative rather than absolute even if we had p-values that had somehow been determined unarbitrarily. If the public, as Briffa seems to be claiming, are unable to understand that science is nuanced rather than black-and-white then I think it is a problem – and not one that is ameliorated in any way by the writings of Dr John Briffa.
You also appear to misrepresent me in suggesting that I have the opinion that science has no value. I don’t hold that view at all, and you would know if you spent just a few minutes trawling my site: it regularly cites scientific evidence.
I must apologise for any misrepresentation of Dr Briffa’s views (funny how he complains about that, when he quotes from a different source than the one I linked to). It just seems to me that there is a contradiction here. P-values are, apparently, arbitrary. This means that scientific evidence is arbitrary. The man who thinks these things then states that he regularly cites scientific evidence on his website. What I’m wondering here is how Dr Briffa decides which studies to cite. Does he cite the arbitrary ones that are deemed to be statistically significant according to those arbitrary p-values? Does he have a special way of sorting the studies himself according to how significant they are on the Briffa Scale? I just don’t understand how someone can claim scientific evidence to be arbitrary and then back up their scientific standpoint by pointing out that they regularly use scientific evidence. Just how arbitrary is the evidence Briffa uses?
So, for the record, I support the concept of science, but I’m no slave to it.
And I also know that one’s experience in practice (in the real world, with real people with their real problems) is important too.
So Briffa’s practice is based in the real world but science isn’t? Maybe I’m in danger of misrepresenting Briffa’s views here, but why would you repeatedly emphasise practice as being ‘real’ (three times in one sentence, and once in a previous comment I quoted) and not science unless you were trying to make some kind of point? The message Briffa’s readers are intended to take away must be, I presume, that science is somehow not part of the real world. Science could probably be summed up as ‘an organised system of knowledge obtained mainly from study of the real world, or nature’. Some may argue with that definition of science, but it most certainly is not divorced from the real world.
So, jdc, perhaps you’d like to share with us some of you clinical expertise. Or is healthcare, for you, an essentially ‘academic’ pursuit? Perhaps you can tell us….
Oh good, it looks like he’s setting himself up for an appeal to authority. Briffa’s clinical expertise clearly enables him to ignore: logic; inconvenient scientific evidence; scientific consensus on p-values and statistical significance. My lack of clinical expertise presumably precludes me from any discussion relating to medical science. Why is ‘academic’ in ‘scare quotes’ though? Is it because he doesn’t think academics are real or something? An indication of sarcasm? Does it indicate some kind of disdain for academics? I’m not sure, but we might come back to ‘academics’ later in the post.
First of all, you suggest that I believe MMR to be unsafe. Actually, I said no such thing. My point is, we can’t be sure that it is safe. Those two positions are not the same.
Briffa’s position has been described by another commentator as boiling down to I’m not saying it does, I’m not saying it doesn’t, I’m just saying – which I have repeated here because I couldn’t have put it any better. Even something as ‘harmless’ as water isn’t safe if you ingest excessive amounts. We can’t ever be 100% sure that any substance is 100% safe. It would be ridiculous to think that we could be and any argument that rests on “we can’t ever be sure it’s safe” is surely doomed. We have to make judgements every day on the risks and benefits of all manner of things and sometimes science can help us to make better-informed decisions as to those risks and benefits – including the risks and benefits of vaccination.
So, jdc, you have drawn our attention to this ‘MMR – the facts’ site, and now perhaps you’d also like to comment on the robustness of the ‘evidence’ this site uses to pronounce MMR as safe, specifically with regard to autism (by the way, it was you that raised the autism issue, not I).
Firstly, the ‘evidence’ Briffa quoted wasn’t on the page I’d linked to. [Seriously – are ‘scare quotes’ meant to give a word pejorative meaning or something? What’s going on with ‘academics’ and ‘evidence’?] Secondly, although it was me who first referred to autism, Briffa’s post used a road accident analagy to state that vaccinations are not always safe and spoke of “a considerable body of people out there who believe (rightly or wrongly) that their child has been damaged by vaccination”. The most prominent groups that believe their child has been damaged by vaccination seem to be groups that believe vaccines cause autism. I think most people would probably think of autism when someone writes about vaccine damage and I’m surprised Dr Briffa (seemingly) didn’t expect anyone to mention autism in relation to his comments on vaccine damage. It seemed to me to be the obvious thing to mention. I know I said I was going to come back to ‘academics’, but Briffa gave a separate response to a second comment I had left on his blog and I might as well make it a separate post. Frankly, I’ll be slightly surprised if anyone is still reading at this point – this post has turned out to be slightly longer than I had intended.