Author: Andrew

Don’t calculate post-hoc power using observed estimate of effect size

Aleksi Reito writes: The statement below was included in a recent issue of Annals of Surgery: But, as 80% power is difficult to achieve in surgical studies, we argue that the CONSORT and STROBE guidelines should be modified to include the disclosure of power—even if less than 80%—with the given sample size and effect size […]

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“Tweeking”: The big problem is not where you think it is.

In her recent article about pizzagate, Stephanie Lee included this hilarious email from Brian Wansink, the self-styled “world-renowned eating behavior expert for over 25 years”: OK, what grabs your attention is that last bit about “tweeking” the data to manipulate the p-value, where Wansink is proposing research misconduct (from NIH: “Falsification: Manipulating research materials, equipment, […]

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Multilevel data collection and analysis for weight training (with R code)

[image of cat lifting weights] A graduate student who wishes to remain anonymous writes: I was wondering if you could answer an elementary question which came to mind after reading your article with Carlin on retrospective power analysis. Consider the field of exercise science, and in particular studies on people who lift weights. (I sometimes […]

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A psychology researcher uses Stan, multiverse, and open data exploration to explore human memory

Under the heading, “An example of Stan to the rescue, multiverse analysis, and psychologists trying to do well,” Greg Cox writes: I’m currently a postdoc at Syracuse University studying how human memory works. I wanted to forward a paper of ours [“Information and Processes Underlying Semantic and Episodic Memory Across Tasks, Items, and Individuals,” by […]

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How to graph a function of 4 variables using a grid

This came up in response to a student’s question. I wrote that, in general, you can plot a function y(x) on a simple graph. You can plot y(x,x2) by plotting y vs x and then having several lines showing different values of x2 (for example, x2=0, x2=0.5, x2=1, x2=1.5, x2=2, etc). You can plot y(x,x2,x3,x4) […]

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Post-publication peer review: who’s qualified?

Gabriel Power writes: I don’t recall that you addressed this point in your posts on post-publication peer review [for example, here and here — ed.]. Who would be allowed to post reviews of a paper? Anyone? Only researchers? Only experts? Science is not a democracy. A study is not valid because a majority of people […]

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A couple more papers on genetic diversity as an explanation for why Africa and remote Andean countries are so poor while Europe and North America are so wealthy

Back in 2013, I wrote a post regarding a controversial claim that high genetic diversity, or low genetic diversity, is bad for the economy: Two economics professors, Quamrul Ashraf and Oded Galor, wrote a paper, “The Out of Africa Hypothesis, Human Genetic Diversity, and Comparative Economic Development,” that is scheduled to appear in the American […]

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The hot hand—in darts!

Roland Langrock writes: Since on your blog you’ve regularly been discussing hot hand literature – which we closely followed – I’m writing to share with you a new working paper we wrote on a potential hot hand pattern in professional darts. We use state-space models in which a continuous-valued latent “hotness” variable, modeled as an […]

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What to do when your measured outcome doesn’t quite line up with what you’re interested in?

Matthew Poes writes: I’m writing a research memo discussing the importance of precisely aligning the outcome measures to the intervention activities. I’m making the point that an evaluation of the outcomes for a given intervention may net null results for many reasons, one of which could simply be that you are looking in the wrong […]

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Don’t get fooled by observational correlations

Gabriel Power writes: Here’s something a little different: clever classrooms, according to which physical characteristics of classrooms cause greater learning. And the effects are large! Moving from the worst to the best design implies a gain of 67% of one year’s worth of learning! Aside from the dubiously large effect size, it looks like the […]

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