Tag Archives: Observational studies

PMean: Cases and cohorts and controls, oh my!

Some asked a question about a retrospective study where you have a control cohort matched to a case cohort so the cohorts are similar on important (potentially confounding) variables. I pointed out that the two consecutive words “case cohort” are ambiguous and tried to explain¬† how I define a retrospective cohort design versus a (retrospective) case-control design. Continue reading

Why secondary data analysis takes a lot longer

Someone posted a question noting that most of the statistical consulting projects that they worked on finished in a reasonable time frame, a few were outliers. They took a lot longer and required a lot more effort by the statisticians. Were there any common features to these outliers they wondered. So they asked if anyone else had identified methodological features of projects that went overtime. I only had a subjective impression, but thought it was still worth sharing. Continue reading

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