1. What is meant by “primary outcome event” and “primary analysis”?
In survival analysis, the outcome event is the one which occurs to complete the survival time. It is the primary outcome event because it is the one which will be used to decide whether there is good evidence of a treatment effect. Ideally, it should be decided before the data are collected, but it should always be decided before the data are looked at.
The primary analysis is the analysis which is decided to be the one which will be used to assess the strength of the trial evidence. Again, it should be stated before the trial is carried out.
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