Variation: Use it or misuse it - Replication and its variants

摘要

In a previous article (Drummond and Vowler, 2012a), we discussed variation between individuals, termed variance. When measurements are taken of subjects in separate groups, the variance of the measurements within the group can be compared with the variance that exists between groups. This allows us to estimate the likelihood that groups were drawn from the same population. Commonly, a treatment has been applied to these groups, and the aim would be to find if this had increased the variance between the groups, wjhich might then indicate that the treatment had caused an effect (Figure 1A).