Thursday, 25 October 2012

Ben pharma

Quite regularly, Marta comes up with some idea to reshuffle something around the house (eg move furniture around, or change the way things are). Normally, mostly because I am a bit lazy, but sometimes because I genuinely don't really see the point, my reaction is to find a logical and rational explanation to why we shouldn't do it. Most of the times, I miserably fail to do so and then we do whatever she plans (in fact, even if I manage to find a reason not to, usually the best I can get is to delay the implementation of the Marta-policy).

At the weekend I ran out of excuses not to move the furniture in the living room (with subsequent ebay bonanza of most of the stuff we have to make way for new exciting things) and so I capitulated. Previously, we had the TV in the top-right corner of the room, with a sofa facing it and an armchair (which I normally sit on) to its left. The new version of the room has the TV in the top-left corner with the armchair now facing it and the sofa to its right.

Obviously, neither I nor the cat liked the changes at first, but the worst thing is that now the two of us are fighting over who gets to sit on the armchair (before, he would sit on the sofa $-$ evidently, like Sheldon Cooper PhD, he just loves that spot). So now, while I sit on (allegedly) my armchair watching telly, or reading my book, I also have to deal with him, patiently looking for his way in to jump on the chair and start pushing me away.

Anyway: the book I'm reading at the moment is Bad Pharma by Ben Goldacre (I've already briefly mentioned it here). It's interesting and I agree with quite a lot that he's arguing. For example, he rants about the fact that trials are often "hidden" by pharmaceutical companies who don't want "unflattering evidence" about their products out for researchers, patients and clinicians to see. This obviously makes like complicated when one tries to put all the evidence in perspective (given that one doesn't have all the evidence to work with...).

But, I have to say (and I'm only in about 100 pages, so just about 1/4 of the book), I don't quite like some of the things he says, or rather the way in which he says them. It seems to me that the underlying assumption is that there is some absolute truth out there (in this case about whether drugs work or not, or have side effects, etc). The problem is that people either hide some evidence, or use biased methods to analyse their data.

For instance, there is an example about a study on duloxetine, in which the industry-led research used last observation carried forward in their analysis. Now, of course we know that this is not ideal and opens up the possibility of crucial bias in the results. But, as far as I'm aware, dealing with missing data is much an art as is a science and there are all sorts of untestable assumptions that have to be included in the model, even when you use a better, more robust, more accepted one. I think this consideration is missing (or at least not clear enough) in Ben's discussion.

I'm not quite of the persuasion that life is 0/1; wrong/correct; all/nothing. To me, the objective of statistical analysis is not to provide facts, but rather to quantify uncertainty. As Lindley puts it, uncertainty is a fact of life, and we just have to deal with it. And statistical modelling is hardly something that goes without uncertainty. Yes we all use Cox's model for survival data, or logistic regression for binary outcomes; but who's to say (in general) that these are the only good ways of modelling these kind of data?

I think that Andrew Gelman makes this point quite often, when he defends Bayesian models vs frequentist ones. Often people tend to criticise the choice of priors, while the data model is considered as an uncontroversial piece of the model, but I agree with Gelman that the prior is only one side of the story. Christian Robert has an interesting post on his blog, in which he quotes a professor of Astrophysics discussing about the role of stats in science.

Anyway, as I said, other than this aspect, I agree with Ben's general message and I'll keep reading the book.

By the way: the living room does look better in its new version.

1 comment:

1. And the cat has won tonight...