CER , can be applied both in pragmaticRCTs (pRCT) and comparative cohort studies. but how to allocate the patients when there are two arms who can take either adjuvant verum or adjuvant placebo with the base of standard care, when there are no studies undertaken on a particular subject. keeping in view the time, money, manpower, rigour, validity involved in RCTs, it is not wise to conduct an double blind RCT at first instance. the first step may be CER-cohort study to generate hypothesis and determine sample size.

should we straight away jump to pilot RCT or begin with CER-cohort study. if the later, what things to be kept in mind while allocating hte patients to two groups with methodological rigour.