I'm a novice in research and wondering if I need to calculate power to determine my sample size. My study is about collecting data from all patients that presented to a clinic for a period of 6 months. Since I am collecting data from all the presentations, would this still require power analysis? If so, could someone guide me on how to do a post hoc analysis as I heard this is the most suitable for a retrospective audit. I believe this is done after the data has been collected to check if the sample size is effective. So would my research proposal just include that a psot-hoc analysis will be completed after data collection has been completed..?
Happy to hear any suggestions if a another power analysis option is more suitable.