Statistically informed ideas on how to make the world work better.

Month: May, 2012

More on why science and the media don’t know much about nutrition, part 1

After my last post, I’ve decided to expand this theme with a series of posts, as many as it takes to deal with this in some depth. This post will largely recapitulate my last comment to Ju-hong on why nutritional studies are harder to get right than other studies. In the process, I will introduce the statistical/epidemiological concepts of interaction and confounding (not the same!). Don’t worry, I promise to make it intuitive!

Imagine you are a researcher interested in seeing if eating grapefruit increases the risk of breast cancer. Why are you interested in this silly, obscure question? Well, it turns out that grapefruit contains chemical compounds that have been shown to increase estrogen levels, and high estrogen levels are thought to increase breast cancer risk. So it’s actually a reasonable question… So what do you do? Well, like any good researcher, you go out and recruit 50,000 post-menopausal women to fill out your surveys on their dietary intake, and then you follow them for a few years to see who gets breast cancer. Kind of morbid? Welcome to epidemiological research…

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Why we shouldn’t trust news stories on scientific studies about what foods are healthy

The blog newsofthetimes has a nice recent post on how new scientific studies are constantly changing conventional wisdom about how to eat healthily. As a health researcher who does some work with nutrition, I have often remarked on exactly the problem she points out, and I have asked myself who is at fault for our rapidly changing guidelines to healthy eating. I think there are largely 2 guilty parties. First is the media. They know that studies like this make good headlines, even when scientists view the results as tentative. They’ve got us jumping this way and that every time there is a new study, which is often.

The second guilty party is researchers themselves (ourselves). We all know that correlation is not causation, and most of the analyses we do go to great lengths to take this into account. But often these lengths are not great enough, or fail to appreciate how complex the world is.

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Why we should punish white-collar criminals more severely than violent criminals



Most of us subscribe to a model of crime and punishment in which we punish criminals with a severity proportional to the nature of the crime, and in particular proportional to the nature of the depravity or bad intentions required on the part of the criminal to commit the crime. This makes intuitive sense – we want to see criminals get their just deserts, and those are very different in the case of a shoplifter and a serial rapist-murderer.

This is, however, a very individualistic perspective that takes into account individual criminals and their intentions and victims. True to form for this blog, I will present a counter-individualistic alternative: that we need to consider much more carefully the larger societal implications of how we punish criminals. More specifically, I argue that we should develop a series of punishments that do not necessarily fit the crimes, but that are best suited to minimizing the impacts of crime on society. A politician who takes a bribe may be more sympathetic than a serial killer, but, indirectly, his action can cost more lives and harm society much more. His punishment should reflect this. The formula I propose: the punishment should fit the large-scale societal impact of the crime, inversely weighted by the probability of getting caught. I’ll explain…

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Statistics, politics, and how we understand the world, or, Are men taller than women?

Ron Paul finally admitted he could not win the Republican presidential nomination in the US.  During this year’s Republican primary, we’ve watched a particular sort of political drama that has become typical. No, I’m not referring to the competition to be the most extreme candidate; I’m referring to the belief that somehow, against all odds, ones preferred candidate will come from behind, defy conventional wisdom, and win.

Rick Santorum, Newt Gingrich, and Ron Paul stayed in the race long after they had lost all real hope of winning. Many of their supporters encouraged this, and refused to concede defeat. This attitude is due, in my opinion, to a pervasive type of ignorance: statistical ignorance. This ignorance causes us to misjudge political races, and has lots of other bad societal consequences as well. Ask yourself the following question: if I flip a coin 100 times, how many heads will I observe?

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Individuals vs. Systems: An underlying philosophy for this blog


The posts on this blog have been, and will continue to be, on a variety of topics, but there are a few underlying principles that infuse my outlook, and will thus infuse many of the posts. Perhaps the most important of these principles is that systems are more important than individuals, and this post is meant to explore that principle and some of its ramifications.

Modern Americans have built their national identity around the philosophy of individualism, and it seeps into American thinking in many ways. The core American values of Democracy, Charity, Capitalism, and Liberty/Freedom are all centered around individualism in one way or another. The most obvious is Freedom, which is interpreted in a modern context as the freedom of individuals to do what they want, regardless of governmental or societal norms. (It’s worth noting that this was not always the case. David Hackett Fischer, in his excellent book Paul Revere’s Ride, makes a strong argument that liberty and freedom for communities was a much stronger value in Revolutionary times. There’s also a growing literature on how too much freedom and choice can paralyze us – see, for example, this great TED talk.)

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When is the stock market right, and when does it reflect mass confusion?

I am somewhat interested in ideas of crowdsourcing and collective wisdom. There are clearly times when the average opinion of lots of normal people is a more reliable predictor than experts. (In fact, there are numerous studies debunking the expertise of experts. But that’s an aside.) There are many examples of this, and the betting market Intrade is one of the principle forums for such collective wisdom, with good histories predicting election results among other things.

But even better known than Intrade are stock markets, which – though designed for other purposes – effectively pool collective wisdom about the values of publicly traded companies, as well as about the state of the economy in general. When a company (or the market in general) is undervalued, savvy individuals will buy in. When it is overvalued, they will sell. We don’t need to know a whole lot about the individual buyers and sellers, since the market effectively averages their opinions into the price of a stock or the level of market indices. But, as we saw during the 2008 US financial crisis, this collective wisdom can be wrong – very wrong – and with grave consequences for the rest of society. So how can we tell these two apart?

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How much should we credit Obama for killing bin-Laden?

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The politicians, news media, and pundits are busy debating these days about how much to credit Obama for killing Osama bin-Laden a year ago. Yes, this is all political grandstanding and campaigning on both sides, but it’s also an interesting question. (We have to take for granted that killing bin-Laden was morally the right thing to do, and that we’re not too squeamish about the incursion into Pakistani territory or other aspects of the means…)

The argument of the right is mostly that anyone would have made the same call. This argument is well refuted by those on the left and those from the security establishment, who argue convincingly that it was a difficult and risky call: many things could have gone wrong and there was little certainty that bin-Laden was in the house. I’d like to make a different and counterintuitive argument: it was precisely because the outcome was uncertain that we should give Obama less credit.

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