Monthly Archives: February 2016

Recommended: Selection of controls in case-control studies

I’m working on a project where the researchers need a case-control study, though they may not know that yet. I want to show them what a case-control study gives them that would not be available with other methods. But I need to come up with a reasonable control group for the case-control design. It doesn’t have to be perfect, but it can’t be a totally stupid control group either. This article is the classic reference on the theoretical principles that underlie the selection of controls in a case-control study. Continue reading

PMean: The problem with incentivizing

I came across a question, “How does your institution incentivize researchers to write more grants?” that was posted a while ago. I felt it was too late to respond directly, but I did want to mention something in my blog about this. “Incentivize” is one of those awful words that used to be a noun (incentive) but has been changed to a verb to make it sound more trendy. That’s something to dislike from the very start, but I have an even greater gripe about incentivizing. Continue reading

PMean: Calculating power for a test of association in a two by two table

A colleague was curious to see the formulas behind the power calculations done by many statistical software programs and online calculators. In particular, she wanted to see the formula used for power of the Chi-squared test of association in a two dimensional contingency table. It gets pretty messy for anything larger than a two by two table, but even a two by two table is a bit tricky. Here ins one mathematical approach that you can choose for a power calculation. Continue reading

PMean: A rant about the “reader pays” model of publication

Something came up in our department about a predatory pay for access journal that was soliciting support. All the appropriate warnings were made (there’s a nice explanation of predatory open access publishing at Wikipedia, if you’re curious). But I felt that I had to made a strong defense of the value provided by legitimate open access publishers. Here’s a summary of what I wrote. Continue reading