Publications by andrew

Post-hoc Pairwise Comparisons of Two-way ANOVA

04.02.2011

I read this post today by John Quick. I was a little taken back when he used a pairwise t-test for post hoc analysis. In a contradiction the t-test did not show differences in the treatment means when the ANOVA model did. This is because the pairwise.t.test does not take into account the two-way anova, it only looks marginally, and so gives e...

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Putting together multinomial discrete regressions by combining simple logits

29.06.2011

When predicting 0/1 data we can use logit (or probit or robit or some other robust model such as invlogit (0.01 + 0.98*X*beta)). Logit is simple enough and we can use bayesglm to regularize and avoid the problem of separation.What if there are more than 2 categories? If they’re ordered (1, 2, 3, etc), we can do ordered logit (and use bayespol...

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Don’t stop being a statistician once the analysis is done

30.06.2011

I received an email from the Royal Statistical Society asking if I wanted to submit a 400-word discussion to the article, Vignettes and health systems responsiveness in cross-country comparative analyses by Nigel Rice, Silvana Robone and Peter C. Smith.My first thought was No, I can’t do it, I don’t know anything about health systems responsi...

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Weighting and prediction in sample surveys

01.07.2011

A couple years ago Rod Little was invited to write an article for the diamond jubilee of the Calcutta Statistical Association Bulletin. His article was published with discussions from Danny Pfefferman, J. N. K. Rao, Don Rubin, and myself. Here it all is.I’ll paste my discussion below, but it’s worth reading the others’ perspectives too. E...

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Experimental reasoning in social science

02.07.2011

As a statistician, I was trained to think of randomized experimentation as representing the gold standard of knowledge in the social sciences, and, despite having seen occasional arguments to the contrary, I still hold that view, expressed pithily by Box, Hunter, and Hunter (1978) that “To find out what happens when you change something, it is ...

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Questions about quantum computing

04.07.2011

I read this article by Rivka Galchen on quantum computing. Much of the article was about an eccentric scientist in his fifties named David Deutch. I’m sure the guy is brilliant but I wasn’t particularly interested in his not particularly interesting life story (apparently he’s thin and lives in Oxford). There was a brief description of q...

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Different goals, different looks: Infovis and the Chris Rock effect

05.07.2011

Seth writes:Here’s my candidate for bad graphic of the year:I [Seth] studied it and learned nothing. I have no idea how they assigned colors to locations. I already knew that there were more within-city calls than calls to individual distant locations — for example that there are more SF-SF calls than SF-LA calls. The researchers took a huge ...

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Early stopping and penalized likelihood

06.07.2011

Maximum likelihood gives the beat fit to the training data but in general overfits, yielding overly-noisy parameter estimates that don’t perform so well when predicting new data. A popular solution to this overfitting problem takes advantage of the iterative nature of most maximum likelihood algorithms by stopping early. In general, an iterat...

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Descriptive statistics, causal inference, and story time

07.07.2011

Dave Backus points me to this review by anthropologist Mike McGovern of two books by economist Paul Collier on the politics of economic development in Africa. My first reaction was that this was interesting but non-statistical so I’d have to either post it on the sister blog or wait until the 30 days of statistics was over. But then I looked ...

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The virtues of incoherence?

08.07.2011

Kent Osband writes:I just read your article The holes in my philosophy of Bayesian data analysis. I agree on the importance of what you flagged as “comparable incoherence in all other statistical philosophies”. The problem arises when a string of unexpected observations persuades that one’s original structural hypothesis (which might be vie...

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