Author Archives: pmean

PMean: Writing the methods section of a research paper

I’m teaching a class on Clinical Research Methodology and at least a few of the students are confused about what to put in the methods section of a research paper or a thesis. They’re confused? I’m even more confused than they are. Every paper and every thesis is different, so it is impossible to offer any coherent guidance. But let me try anyway. Continue reading

Recommended: What would Florence Nightingale make of big data?

This is a nice video, professionally produced and very short (4 minutes) that shows the importance Florence Nightingale attached to Statistics. It reviews how she used Statistics aggressively to lobby for improvements to health care, and speculates on what she would think about the efforts today to use big data for decision making. The narrator is David Spiegelhalter, a famous statistician. Continue reading

Recommended: Case for omitting tied observations in the two-sample t-test and the Wilcoxon-Mann-Whitney Test

When you are running a non-parametric test, like the Wilcoxon-Mann-Whitney test, you can only be 100% of the properties of that test (including Type I and Type II error rates) if the data are continuous. If there are ties in the data, the properties of the test are unknown. This paper shows four commonly used approaches for settings where values might be tied and runs simulations to measure Type I and Type II error rates for both the two-sample t-test and the Wilcoxon-Mann-Whitney test under a range of tied values and a range of distributions. The results are, at least to me, quite surprising. Continue reading