Propensity scores represent an intriguing alternative method to reduce the impact of confounding variables, especially when there are multiple potential confounding variables. This paper considers a range of models comparing the propensity score approach to the more traditional approaches of adjusting for confounders. I think the conclusions are overly simplistic, but the paper is still worth reading. Continue reading
Monthly Archives: December 2013
PMean: Sample size for comparing two diagnostic tests
I had a client come in with a sample size question. It involved the comparison of two diagnostic tests to a gold standard. There a couple of different ways to attack the problem. Continue reading
Recommended: Study Development (Kansas City area resource)
This is an excellent local resource for those of you in the Kansas City area. They have guidance on coming up with a study idea, finding funding, and identifying study participants. This site offers general information and links to resources with Frontiers (aka the Heartland Institute for Clinical and Translational Research). Continue reading
Recommended: DataMind website
DataMind is a website offering free tutorials for the R programming language and tools that let you develop your own tutorials based on R Markdown. I have not tested any of this, but it looks interesting. Continue reading
PMean: Claims lacking specificity are meaningless
I recently encountered a claim about the unlimited applications for a new statistical model. I, for one, tend to view “unlimited applications” as a negative comment rather than a positive comment. Any new model that pretends to be applicable in all areas is probably applicable in no areas. Here’s why. Continue reading
Recommended: Use = or <- for assignment?
I learned R back when the only way to assign a value was with the <- operator. For example, if you were computing the hypotenuse of a triangle, you’d use c <- sqrt(a^2+b^2). But the language now allows you to use an equals sign instead, which is the choice in many other programming languages. Should you do this? I say “no” emphatically, but this website makes an interesting counter-argument. Continue reading
PMean: Is Possibility Theory better than Probability Theory?
Someone on a LinkedIn group posted a question about “Possibility Theory.” The question itself had a lot of hype, claiming that “time has expired for Probability Theory.” Still, it is an interesting question and here’s how I responded. Continue reading
Recommended: “Any other comments?” Open questions on questionnaires – a bane or a bonus to research?
This is a classic reference that is worth re-posting. No one seems to know what to do about those pesky open-ended questions you see on a survey. This article offers practical tips on how to handle this type of data. Continue reading
PMean: The cost of a bad prediction
Paul Krugman wrote up an interesting application of Bayes Theorem on his blog on the New York Times. I want to adapt his example and expand it a bit. Continue reading
Recommended: How confidence intervals become confusion intervals.
The desire among researchers for a black and white dichotomy between “significant” and “not significant” results leads to a lot of unnecessary confusion. Continue reading