michael_b comments on Welcome to Less Wrong! (7th thread, December 2014) - LessWrong

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Comment author: michael_b 29 January 2015 04:58:42PM *  2 points [-]

Yes. I spent a lot of time reviewing critiques of The China Study (TCS), including Minger's. At the end of it I came to the following conclusions.

  1. Nutrition science is extraordinarily nonlinear
  2. I'm definitely not qualified to deconstruct claims made about nutrition
  3. TCS critics don't seem very qualified either, especially when compared to the qualifications of the people advancing TCS
  4. There's no larger group of qualified people advancing a radically different approach

So, those are my reasons. I admit they're not very satisfying. I'm spoiled by fields where, once you grok the formal proof you can be highly confident that the claim is correct.

No such luck with something as squishy as nutrition, it would seem.

Comment author: IlyaShpitser 29 January 2015 05:29:32PM 4 points [-]

General advice: learn causal inference. Getting strong causal claims empirically is not so simple...

Comment author: Lumifer 29 January 2015 05:09:47PM 1 point [-]

I disagree with your approach (basically, trust authority), but that's just me.

Comment author: dxu 29 January 2015 06:36:05PM 2 points [-]

When you know next to nothing about the topic at hand and the only choice is to trust authority or to rely on your own, almost certainly flawed judgment, I'd go with authority.

Comment author: Lumifer 29 January 2015 06:58:15PM 1 point [-]

When you know next to nothing about the topic at hand and the only choice is to trust authority or to rely on your own, almost certainly flawed judgment, I'd go with authority.

When the topic is an important one, like health and nutrition, I'll go learn about the topic.

Comment author: michael_b 29 January 2015 10:51:34PM *  2 points [-]

I'm skeptical this is a great strategy for topics in general.

Nutrition, for example, doesn't appear to be the kind of topic where you can just learn its axioms and build up an optimal human diet from first principles. It's far too complicated.

Instead you need substantial education, training, experience and access, as well as a community that can help you support and refine your ideas. You need to gather evidence, you need to learn how to determine the quality of the evidence you've gathered, and you need to propose reasonable stories that fit the evidence.

Since I haven't made health and nutrition my career most of these things will be hard or even impossible for me to come by. As such, my confidence in the quality of any amateur conclusions I come to must necessarily be low.

So, the most reasonable thing for me to do is trust authorities when it comes to nutrition.

Comment author: Lumifer 30 January 2015 04:32:22PM *  2 points [-]

I'm skeptical this is a great strategy for topics in general.

And rightly so :-) This is an approach that should be reserved for important topics.

Instead you need substantial education, training, experience and access, as well as a community

I think you're setting the bar too high. What you describe will allow one to produce new research and that's not the goal here. All you need to be able to do is to pass a judgement on conflicting claims -- that's much easier than gathering evidence and proposing stories.

In nutrition, for example, a lot of claims are contested and not by crackpots. Highly qualified people strongly disagree about basic issues, for example, the effects of dietary saturated fat. I am saying that you should read the arguments of both sides and form your opinion about them -- not that you should apply to the NIH for a grant to do a definitive study.

Of course that means reading the actual papers, not dumbed down advice for hoi polloi.

Comment author: dxu 29 January 2015 07:50:43PM *  1 point [-]

By "learn", I assume you mean read existing literature on the topic. In the case of health and nutrition (and most other medical topics), high-quality literature is rather sparse, both because of frequently bad statistical analyses and the fact that practically no one releases their raw data--only the results. (Seriously, what's up with that?)

Comment author: Lumifer 29 January 2015 08:10:44PM 2 points [-]

By "learn", I assume you mean read existing literature on the topic

Also around the topic, not to mention that learning necessarily involves a fair amount of one's own thinking.

high-quality literature is rather sparse

I agree which makes relying of authority (and, usually, on mass media reinterpretations of authority) particularly suspect.

what's up with that?

I think the usual explanation is privacy and medical ethics, but my cynical mind readily suggests that it's much harder to critique a study if you can't see the data...

Comment author: Nornagest 29 January 2015 08:11:14PM *  3 points [-]

Given that the experts in the field are precisely those learning from and producing that same literature, the fact that the literature is generally low-quality doesn't make me more inclined to trust them. (Though, as bad as academic nutrition science is, conventional wisdom and pop nutrition science seem to be worse.)

It does make it exceptionally hard to gain a good understanding of the field yourself, though. Unlike Lumifer, I'd say the correct move, unless you are yourself a nutritionist or a fitness nerd or otherwise inclined to spend a large portion of your life on this, is to reserve judgment.

Comment author: dxu 30 January 2015 04:35:37PM *  0 points [-]

Given that the experts in the field are precisely those learning from and producing that same literature, the fact that the literature is generally low-quality doesn't make me more inclined to trust them.

In terms of statistics and data, yes, the papers they produce are fairly low-quality. In terms of domain-specific knowledge, however, I'd trust an expert over pretty much anyone else. That being said, I do agree with you here:

It does make it exceptionally hard to gain a good understanding of the field yourself, though. Unlike Lumifer, I'd say the correct move, unless you are yourself a nutritionist or a fitness nerd or otherwise inclined to spend a large portion of your life on this, is to reserve judgment.

Although I prefer trusting expert authority to making my own judgments on unfamiliar topics, gaining a good-enough understanding to figure out which experts to trust is still hard, especially with so many conflicting conclusions out there. This being the case, the strategy you propose--reserve judgment--is precisely what I do.

Comment author: Lumifer 30 January 2015 05:22:28PM 2 points [-]

In terms of domain-specific knowledge, however, I'd trust an expert over pretty much anyone else.

That doesn't help you when experts disagree.

Comment author: Lumifer 29 January 2015 08:15:09PM 0 points [-]

is to reserve judgment

You can't -- you've got to eat each day :-/

Comment author: Nornagest 29 January 2015 08:21:09PM *  1 point [-]

Ah, the old "choosing not to choose is itself a choice" move. Never was too convinced by that.

You can reserve judgment on the theory while taking some default stance on the practical issue. Depending on where you're standing this might mean the standard diet for your culture (probably suboptimal, but arguably less suboptimal than whatever random permutations you might apply to it), or "common sense" (which I'm skeptical of in some ways, but it probably picks some low-hanging fruit), or imitating people or populations with empirically good results (the "Mediterranean diet" is a persistently popular target), or adopting a cautious stance toward dietary innovations from the last forty years or so (about when the obesity epidemic started taking off).

Comment author: Lumifer 29 January 2015 08:27:23PM 1 point [-]

Never was too convinced by that.

It looks obviously true to me.

while taking some default stance on the practical issue

Your stance is a choice nevertheless and it necessary implies a particular theory of nutrition (even if that theory is not academically recognized and might be as simple as "eating whatever everyone else eats can't be that bad").

Comment author: Nornagest 29 January 2015 08:30:04PM *  2 points [-]

It's an option -- a point in a configuration space -- but not a random option. The default is, almost tautologically, a stable equilibrium, while in a sufficiently complicated system almost all possible choices may move you away from that equilibrium in ways you don't want.

Nutrition is a very complicated system. Of course, its fitness landscape might be friendlier than I'm giving it credit for here, but I don't have any particular reason to assume that it is.

Comment author: [deleted] 29 January 2015 05:38:28PM 0 points [-]

Sounds to me that you're trusting authority that just happens to be of a different sort.

Comment author: Lumifer 29 January 2015 05:50:41PM 1 point [-]

No, I do not. I actually read the papers and see if they make sense. One of my long-standing complaints is that in medical research no one releases the data -- it would be very useful to reanalyze it is a bit less brain-dead fashion.

Comment author: [deleted] 29 January 2015 05:56:36PM 0 points [-]

Then why'd you recommend Minger's criticism? Because as far as I can tell it doesn't make sense.

Comment author: Lumifer 29 January 2015 05:59:17PM 1 point [-]

Makes a lot of sense to me. What is it that doesn't make sense to you?

Comment author: [deleted] 29 January 2015 06:02:44PM *  0 points [-]

Let's start with the sturm and drang over Tuoli, I suppose. Why aren't they an obvious outlier?

Comment author: Lumifer 29 January 2015 06:14:19PM 2 points [-]

Um, it is.

To quote Minger

Using the data set with the flawed inclusion of Tuoli, Campbell cites a strong association between animal protein and lipid intake as a reason to implicate animal foods with breast cancer. Yet using the revised data set, animal foods do not contribute significantly more fat to total lipid intake than do plant oils. As a result, any association between breast cancer and dietary fat could be linked to either animal or plant-sourced foods, and there is no justification for indicting only animal products.

Also, to continue quoting Minger,

..meat was not the dietary feature noted in my discussion of Tuoli: dairy was. Both the three-day diet survey and the frequency questionnaire reveal high intakes of dairy for Tuoli citizens, with the questionnaire indicating milk products are consumed an average of 330.3 days per year, and closer to 350 in one township.[98] In addition, despite Campbell’s comment that the Tuoli migrate seasonally and consume more vegetables and fruit for part of the year, the China Study frequency questionnaire indicates Tuoli’s vegetable intake is only twice per year and fruit intake is less than once per year on average.[99]

If Campbell believes both the three-day diet survey and frequency questionnaire were in error, I must question why Tuoli county was not excluded entirely from the data set—especially given its pronounced influence on virtually all associations involving meat, dairy, and animal protein, many of which Campbell cited as verification for his animal foods-disease hypothesis.

Comment author: [deleted] 29 January 2015 06:31:21PM 0 points [-]

Yet elsewhere:

Why aren’t [the people who live in Tuoli] sick and diseased?

We have plenty of evidence showing hormone-pumped dairy, grain-fed meat, pasteurized and homogenized milk, processed lunch meats, and other monstrosities are bad for the human body. No debate there. But we do have a woeful lack of research on the effects of “clean” animal products—meat from wild or pastured animals fed good diets, milk that hasn’t been heat-zapped, antibiotic-free cheeses and yogurts, and so forth.

[...]

Is it possible the diseases we ascribe to animal products aren’t caused by animal products themselves, but by the chemicals, hormones, and treatment processes we expose them to? If the Tuoli are any indication, this may be the case. Hopefully future research will shed more light on the matter.

Or, you know, they're an insular minority with peculiar nutritional requirements.

Comment author: Lumifer 29 January 2015 06:54:10PM *  1 point [-]

You said that Minger's criticism of TCS "doesn't make sense". Did you actually have anything specific in mind?

I also don't see much problems with the passages you quoted.

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