[Solved]: How is Interim analysis defined

How is Interim analysis defined? 1 The estimation how many patients or people need be enrolled in a specific research 2 An evaluation of the current data from an ongoing trial, in which the primary research question is addressed, and which has the potential for modifying the conduct of the study. 3 The difference in the effects of two treatments 4 The conclusive proof that two treatments have different effects. 5 Prognostic factors affecting the treatment effect