which study is a nested case control what is the challenge of case cohort why is my study no longer a case cohort why is it difficult to follow up on a case cohort design quizlet why case cohorts are not nested why do we have a case cohort design why is there no case cohort how long would followup update take to occur in a study when do follow up updates become necessary how to do follow up updates in case cohort why would a controlled trial not be considered a case cohort in research studies? is the study a case cohort are nested case controls used in research how to make a cohort study a true case study when is a case cohort sampled and added to the study? what's the challenge of a case cohort? what is the difference between cohort and sub-cohort research? why is it difficult to make a cohort study why would a study become a case cohort? why is it a case cohort?