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Too much of nothing

Is more placebo better? A friend of mine pointed me to the above TED talk, by Ben Goldacre. It's a entertaining presentation with lots of interesting content, although Goldacre's discussion of the placebo effect—"one of the most fascinating things in the whole of medicine" (6:32)—is a little weak. At 6:47, he says: We know for example that two sugar pills a day are a more effective treatment for getting rid of gastric ulcers than one sugar pill a day. Two sugar pills a day beats one pill a day. And that's an outrageous and ridiculous finding, but it's true. Notice that the claim is not about pain , but about actually healing the ulcers. The source of this claim is apparently a 1999 study by de Craen and co-authors titled "Placebo effect in the treatment of duodenal ulcer" [ free full text/pdf ]. It's a systematic review based on 79 randomized trials comparing various drugs to placebo, taken either four times a day or twice a day depending o...

The placebo defect

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Suppose a clinical trial randomizes 100 patients to receive an experimental drug in the form of pills and an equal number of patients to receive identical pills except that they contain no active ingredient, that is, placebo. The results of the trial are as follows: 60 of the patients who received the experimental drug improved, compared to 30 of the patients who received the placebo. The drug clearly works better than the placebo. [1] But 30% of the patients who received the placebo did get better. There seems to be a placebo effect, right? Wrong. The results from this trial provide no information about whether or not there is a placebo effect. To determine whether there is a placebo effect you would need compare the outcomes of patients who received placebo with the outcomes of patients who received no treatment. And not surprisingly, trials with a no-treatment arm are quite rare. But there are some. In a landmark paper published in the New England Journal of Medicine in 2001 ( fre...

Rethinking property

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Suppose Alison has been playing a game of solitaire, but has left the room. A little while later, Trevor, aged 4, notices the cards lying on the table and reaches for them. Another member of the family calls out, "Trevor, don't touch those, they're Alison's!" A straightforward case of teaching a young person about property rights, isn't it? Perhaps not. The deck of cards may belong to the family rather than just Alison. And in any case, it's really not the ownership of the cards themselves that's the issue, it's their arrangement on the table. If that arrangement is significantly disturbed , the game will be ruined even if the cards themselves are not at all damaged. So why do we construe this as an issue of property rights? I believe the reason is that we find it much easier to express property claims than to describe the real issue, which is respect for other people. Perhaps we might have said, "Trevor, don't touch those, Alison is play...

The landscape of probability

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We all know that the probability of some condition can lie anywhere between a sure thing (which we represent as a probability of 1) and a flat-out impossibility (0). But it turns out there are several other points of interest along the way. Let's take a tour. When we say that something is a sure thing, we mean it is bound to be so. For example, the probability that a bachelor is unmarried is 1. This is a logical sure thing because, by the definition of 'bachelor', it couldn't be otherwise. (It could also be called an apodictic sure thing, however that's pretty much guaranteed to sound pretentious—but I'm getting ahead of myself.) Now consider the statement that an object with a positive electrical charge is attracted to an object with a negative electrical charge. This is a physical sure thing : though there may be a universe where this isn't true, it is true in ours. Now let's move from sure things to things that are pretty much guaranteed . For ex...

The fragmentary nature of television

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For the past couple of months, I've been reading, and thinking about phenomenology , a philosophical movement concerned with the nature of conscious experience. My guide has been the wonderful Introduction to Phenomenology by Robert Sokolowski. I haven't found it easy to understand phenomenology, nor have I found it easy to explain to other people, but I am finding it to be a very rich source of insight. As I was watching a television show the other night (Vampire Diaries, if you must know), I suddenly made a connection with something I had read in Sokolowski's book: One of the dangers we face is that with the technological expansion of images and words, everything seems to fall apart into mere appearances. ... it seems that we now are flooded by fragments without any wholes, by manifolds bereft of identities, and by multiple absences without any enduring real presence. We have bricolage and nothing else, and we think we can even invent ourselves at random by assembling c...

Causal language

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Consider the following sentence: " You ate the blueberries because your fingers are stained." What is odd about it is that ordinarily, when we say "X because of Y" we mean "Y is the cause of X". For example, "The window broke because the baseball hit it" means that the baseball hitting the window caused it to break. But in this case, the sentence surely doesn't mean that your fingers being stained caused you to eat the blueberries. Now one might object that it's a weird sentence, and that instead it should be " I believe you ate the blueberries because your fingers are stained. " But the original version is not confusing to an English speaker, and people sometimes do speak this way. Language is a complicated business. And language about causality is particularly tricky. It is well known that correlation does not imply causation . But when scientific studies are reported in the media, this dictum is often forgotten. Professor...

Chance and inevitability

In an op-ed in today's issue of the Los Angeles Times, Michael Shermer wrote about the rush "to find the deep underlying causes of shocking events", with reference to the shooting in Tucson, Arizona and the recent mass bird deaths. Shermer made some good points, but parts of his argument were flawed. For example, he cited statistics from the National Institute of Mental Health to argue that unbalanced people are not uncommon, and Given these statistics, events such as the shooting in Tucson are bound to happen, no matter how nicely politicians talk to one another on the campaign trail or in Congress, no matter how extreme tea party slogans are about killing government programs, and no matter how stiff or loose gun control laws are in this or that state. By chance — and nothing more — there will always be people who do the unthinkable. In other words, he is pointing out what he sees as an inevitability, and then attributing it to chance. But an inevitability is the opposi...