In an April 30, 2015 note in Nature (vol 520, p. 612), Jeffrey Leek and Roger Peng note that p-values get intense scrutiny, while all the decisions that lead up to the p-values get little debate. I wholeheartedly agree, and so I'm creating a Littl...
Recently, I had to simulate a time-to-event of subjects who have been on a study, are still ongoing at the time of a data cut, but who are still at risk of an event (e.g. progressive disease, cardiac event, death). This requires the simulation of a con...
“Reproducible” and “randomized” don’t seem to go together. If something was unpredictable the first time, shouldn’t it be unpredictable if you start over and run it again? As is often the case, we want incompatible things. But the combination of reproducible and random can be reconciled. Why would we want a randomized controlled trial (RCT) to […]
The article Deming, data and observational studies by S. Stanley Young and Alan Karr opens with Any claim coming from an observational study is most likely to be wrong. They back up this assertion with data about observational studies later contradicted by prospective studies. Much has been said lately about the assertion that most published results are false, particularly […]
This week, a study was published that claimed that the placebo response is mediated by genetics. Though I need to dig a little deeper and figure out exactly what this article is saying, I do think we need to take a step back and remember what can const...
In a dose-finding clinical trial, you have a small number of doses to test, and you hope find the one with the best response. Here “best” may mean most effective, least toxic, closest to a target toxicity, some combination of criteria, etc. Since your goal is to find the best dose, it seems natural to compare dose-finding […]
-+*When you sort data and look at which sample falls in a particular position, that’s called order statistics. For example, you might want to know the smallest, largest, or middle value. Order statistics are robust in a sense. The median of a sample, for example, is a very robust measure of central tendency. If Bill […]
Recently, I was working with a team to finalize a clinical trial protocol. I raised some concerns about their strategic matters, and my concerns were dismissed as "operational details."The thing about those pesky operational details is that, if somethi...
When I hear someone say “personalized medicine” I want to ask “as opposed to what?” All medicine is personalized. If you are in an emergency room with a broken leg and the person next to you is lapsing into a…Read more ›
Someone asked me yesterday how people justify probability distribution assumptions. Sometimes the most mystifying assumption is the first one: “Assume X is normally distributed …” Here are a few answers. Sometimes distribution assumptions are not justified. Sometimes distributions can be…Read more ›
