The main activity in the course is the analysis of datasets. Weekly classes are devoted to a discussion of work in progress and a review of plans for the next week. We insist that each group present its thinking and its results to all students, and all students are expected to contribute to a discussion of what to do next. Even before we begin any analysis, there is usually lively discussion about the primary contrast. We find that students in epidemiology are very aware of the possibilities of biased comparisons when using largely non-experimental data.
Some students say that it is an intermediate variable.
A few students muse about how it was measured. We discuss whether the heteroscedasticity introduces bias and whether it leads to incorrect estimates of the precision of fitted coefficients or of individual variability. 13 Students have recently analyzed the data using techniques from survival analysis. Some students have not considered survival analysis techniques because there are no censored observations.