First meeting - 8 September

We held our first meeting yesterday to discuss an old, but relevant paper by Stephen Senn. Here's a link to the abstract:

Testing for baseline balance - Stephen Senn

Our discussion revolved around a number of issues highlighted in the paper. We wondered whether or not it's necessary to add a 'Table 1' to a publication, and although some of the members thought it was useful to add a table describing patient characteristics, other felt it's generally unnecessary to conduct significance tests to highlight differences between two groups in clinical trials or case control studies. Although baseline tests may demonstrate that the randomization hasn't worked, it's very easy to manipulate randomization and maintain baseline balance in a clinical trial.

We also talked about how to decide what covariates to add to an analysis. The paper specifically advises readers to choose covariates based on previous studies, and fit those covariates in multivariable regression techniques whatever the degree of imbalance in the baseline tests. This approach was generally well received, and we talked about some of the issues around covariate selection. Some of the members were experienced in using causal diagrams and directed acyclic graphs, so we thought that this might be an interesting area to discuss in a future seminar.

Since this was the first meeting, I thought it would be a good idea to think forward and discuss ideas for future meetings. Areas for future discussions could include Mendelian randomization and approaches to missing data. I'd like to also invite speakers to discuss their own work, so if you have any ideas or would like to discuss your own work in progress, email me at nada.khan@dphpc.ox.ac.uk.

Next meeting is on October 21!