Coffee drinking linked to longer life • Hacker News Board

Re: Coffee drinking linked to longer life

#21

Post by cjbprime » Thu, May 17, 2012, 4:07 PM UTC

Cushman wrote: post #12

cynicalkane wrote: post #7

Earlier quoted context omitted.

Like almost everyone else who will comment here, I haven't read the study, but studies normally statistically control for these sorts of things.

Thanks for that. It's a little annoying that every time a study like this comes up, somebody jumps in with "Well, did they control for [obvious thing to control for]?" You don't become a scientist because you're lazy and stupid. If you're reading about a study and think there's an obvious reason it's inaccurate, you are almost certainly wrong. Not that the study is not inaccurate -- many, perhaps most are -- but the…

Guess what: it looks like the authors didn't control for income (or even just whether the person has a job!) or intelligence.

I just read the paper; there are many diet and exercise-related controls, and that's it as far as I can see. I totally agree with the OP that being the kind of person who might drink coffee probably has a confounding effect on health. I can't even think of how to try to control it properly.

I don't understand how you get from "most studies are inaccurate" to "but you shouldn't assume the ones that get reported on in the media are inaccurate in a way that we can detect". Why not? People who are performing studies that get picked up by popular media are the least likely people to be performing their work rigorously, and the most likely to be choosing a sensational hypothesis that's difficult to measure correctly.

I agree that we might eventually get to a point where the amount of skepticism and cynicism about scientific results vastly outweighs the number of papers published with poor experimental design or lack of real statistical significance. But I don't think we're currently anywhere close!

Re: Coffee drinking linked to longer life

#22

Post by Cushman » Thu, May 17, 2012, 4:09 PM UTC

imurray wrote: post #13

ryandvm wrote: post #3

My guess is that if you're drinking 6 cups of coffee a day, you've probably got yourself a nice white collar job - and a lot of the other life lengthening perks that come along with gainful employment.

Indeed. This type of study, while really popular in the press, is often horribly confounded and hard to control for. I think the hacker news audience mostly knows to be skeptical, so I don't know why it was submitted. I'll use this post as an excuse to mention the Lothian Birth Cohort. A really cool dataset of IQ test results at age 11 for (almost) all Scottish kids born in 1921 and 1936. While IQ tests are flawed in…

In response to your edit: I think you're saying something very different than what your sibling responded to. The parent's claim was "They didn't correct for X"; your claim is "They tried to correct for X, but we have no way of knowing if they did it right."

The difference is that what you're saying is true of any study. There are always obvious things to control for, and less-obvious ones, and the authors always try and sometimes they do it right and sometimes they don't and there's never any way to tell for sure without redoing the study[0].

The fact that a layman reading a mainstream article about the study can come up with a possible confounding factor doesn't imply much if anything about its possible veracity. We should be equally suspicious of all such claims, not only those which happen to have flaws which are apparent to us.

[0] If the study contains a basic statistical error, redoing it might just be a matter of reinterpreting the original data; still counts.

Re: Coffee drinking linked to longer life

#23

Post by eslachance » Thu, May 17, 2012, 4:11 PM UTC

ryandvm wrote: post #3

My guess is that if you're drinking 6 cups of coffee a day, you've probably got yourself a nice white collar job - and a lot of the other life lengthening perks that come along with gainful employment.

It would be interesting if the study showed this, but since the article doesn't mention it, that's a bit of an assumption you're making here.

I personally know a couple of heavy coffee drinkers, some of them should be retired but still work blue collar jobs (one is a roofer, another is a general contractor). I doubt they would agree with you on this one :)

Re: Coffee drinking linked to longer life

#24

Post by Cushman » Thu, May 17, 2012, 4:23 PM UTC

cjbprime wrote: post #21

Cushman wrote: post #12

Earlier quoted context omitted.

Thanks for that. It's a little annoying that every time a study like this comes up, somebody jumps in with "Well, did they control for [obvious thing to control for]?" You don't become a scientist because you're lazy and stupid. If you're reading about a study and think there's an obvious reason it's inaccurate, you are almost certainly wrong. Not that the study is not inaccurate -- many, perhaps most are -- but the…

Guess what: it looks like the authors didn't control for income (or even just whether the person has a job!) or intelligence. I just read the paper; there are many diet and exercise-related controls, and that's it as far as I can see. I totally agree with the OP that being the kind of person who might drink coffee probably has a confounding effect on health. I can't even think of how to try to control it properly. I…

You make some good points, so I hope this doesn't seem dismissive-- my claim is not that the study is right. My claim is simply that the editors of the NEJM decided to publish the study having read it in greater depth than any of us here would care to, so if I read the CNN article and think there's an obvious reason it's not true, I can be pretty sure I'm wrong.

Now that being said, I think we're talking at cross purposes. The study found a link between coffee drinknig and mortality; I misread the GGP as being critical of that link, where it's actually just a hypothesis which would explain it. So none of this is really relevant :P

Re: Coffee drinking linked to longer life

#25

Post by Someone » Thu, May 17, 2012, 6:17 PM UTC

hogworth wrote: post #8

Gosh I hope this doesn't come off as too negative, but what is the point finding these 'links'? Science is about trying to explain the world, not looking for random facts. We learn nothing of substance about coffee, health or anything else from this article. Yet it has the appearance of being scientific, for example, it mentions antioxidants. It wouldn't be fair to label it pseudoscience however it does share some of…

Do you know on how many centuries of tabulating 'links' Newton, Darwin, and Einstein built their work? Apart from modesty, there is truth in Newton's claim about standing on the shoulders of giants.

Also, this is not a random fact. People have argued both ways whether coffe is healthy or not. If we want doctors to give advice based on facts, we have to, somehow, figure out who (if anybody) is right there. Barring a clear mechanism either way, looking for facts is a step towards scientific understanding.