There is a fashion for producing eye-catching infographics of trial results. This is a good thing in some ways, because it’s important to get the results communicated to doctors and patients in a way they can understand. Here’s one from the recent WOMAN trial (evaluating tranexamic acid for postpartum haemorrhage). What’s wrong with this? To my mind … Continue reading Trial results infographics
I just did a project with a work experience student that involved looking back through four top medical journals for the past year (NEJM, JAMA, Lancet and BMJ), looking for reports of randomised trials. As you can imagine, there were quite a lot - I'm not sure exactly how many because only a subset were … Continue reading The future is still in the future
One of the consequences of the perceived need for a “primary outcome” is that people try to create a single outcome variable that will include all or most of the important effects, and will increase the incidence of the outcome, or in some other way allow the sample size calculation to give you a smaller … Continue reading Hospital–free survival
Here’s a photo of a slide from a talk by Doug Altman about hypothesis tests and p-values recently (I nicked the picture from Twitter, additions by me). I wasn’t there so I don’t know exactly what Doug said, but I totally agree that hypothesis testing and p-values are a massive problem. Nearly five years ago … Continue reading Rant
Here are a couple of statements about the justification of the sample size from reports of clinical trials in high-impact journals (I think one is from JAMA and the other from NEJM): We estimated that a sample size of 3000 … would provide 90% power to detect an absolute difference of 6.3 percentage points in the rate of … Continue reading Sample size statement translation
Follow-up to The Fragility Index for clinical trials from Evidence-based everything I’ve slipped in my plan to do a new blog post every week, but here’s a quick interim one. I blogged about the fragility index a few months back (http://blogs.warwick.ac.uk/simongates/entry/the_fragility_index/). Andrew Gelman has also blogged about this, and thought much the same as I did (OK, I … Continue reading Andrew Gelman agrees with me!
One of the places that Bayesian methods have made some progress in the clinical trials world is in very rare diseases. And it’s true, traditional methods are hopeless in this situation, where you can never get enough recruits to get anywhere near the sample size that traditional methods demand for an “adequately powered” study, and … Continue reading Bayesian methods and trials in rare and common diseases