Hold me now, I'm hoping that you can explain

[venta]

Yesterday, I pottered along to the Barbican to see what was going on at their Brainwaves Weekender. Among other things, I parked myself on the floor to watch Helen Arney present the unappealingly-titled I'm a Neuroscientist, Get Me Out Of Here!.

I'd have titled it "Listen to five smart people, who are neuroscientists, talk entertainingly and informatively about their subject". Which isn't as snappy, but there you go. Anyway, they were entertaining and informative.

Annoyingly, the bit that has really stuck with me is a silly little niggle. At the beginning of the 45 minute session, each of the tame neuroscientists was invited to present two "facts" for the audience to guess which was true and which was false. One of the neuroscientists, whose subject was research into Alzeimher's disease, stated "You are more likely to get Alzheimer's if you have a relative who suffers from it".

This was revealed to be her untrue "fact". She said that actually, the biggest risk factor for Alzheimer's was getting old. Most cases of Alzheimer's just occur spontaneously. Only 1 in 20 cases are hereditary, so people who worry a lot about developing it because they have relatives with dementia are worrying unnecessarily.

Now, I'm pretty sure that we're all at equal risk of getting old and developing a spontaneously-occuring disease. And for those who have a relative with Alzheimer's, there's that extra chance of it being a hereditary trait. So actually, by my reasoning, you genuinely are more likely to get Alzheimer's if you have a relative who suffers from it. Possibly not massively more likely, but more likely. Her untrue "fact" was actually a true fact.

Scientists who don't seem to understand stats and probability scare me :(

Comments

[venta.livejournal.com]

Now, I'm pretty sure that we're all at equal risk of getting old and developing a spontaneously-occuring disease

OK, for pedants: I realise that isn't strictly true!

[bopeepsheep.livejournal.com]

If you have a relative who has lived long enough to get Alzheimers, I believe this ups your chance of living to a great age too (the longer your grandparents and great-grandparents lived, the longer you are predicted to live, etc). So yes, it makes sense to me that - correlation, not causation - a lot of elderly relatives with Alzheimers means you are also likely to become an elderly Alzheimers patient. I suspect it's not true that early onset Alzheimers in a relative puts you at any increased risk. (But if that's what she meant she should have said so.)

[bateleur.livejournal.com]

Scientists who don't seem to understand stats and probability scare me :(

I advise you not to investigate the field too closely. I wasn't even good at stats at uni and I have so far encountered so few scientists who understand stats properly that I can literally count them on the fingers of one hand. (Admittedly accompanied by many more for whom I don't know either way.)

The big problem is that scientists fall into two categories:

1) Those who don't work with stats. It's not too surprising they don't have much grasp of the finer points.
2) Those who do work with stats. And the trouble here is that they have been given rote methods to use, which they don't understand, but are prepared to argue for.

Result: When actual understanding is needed, they all come unstuck.

This is something of a rant topic for me, since I get very tired of explaining correlation vs causation to people who ought to know better. (Bonus points if they respond "Yes, of course I know the difference, but what are the chances that we have all this evidence when there's no causal link?") And don't even get me started on scientists saying "No, don't worry, we adjusted for that" when all they mean is that they did a linear regression. (Bonus points in this case for "No, it's not linear, it's multivariate!")

[lathany.livejournal.com]

Scientists who don't seem to understand stats and probability scare me :(

Yeah, they scare me too.