It is time for us to now think over how many subjects we have to study to answer our research question- the sample size.
We do not want to study more than necessary or less than the required number of subjects. We want an appropriate sample size that is based on our research question and study designs and methods and provides us with answers that can withstand scrutiny.
I am sharing some concepts that I follow when I estimate a sample size (there are times I follow a different direction but this is the most common path I take). I am not going into a detailed statistical description here- there are enough internet resources for the same.
Please feel free to critically analyze, adapt or adopt as you see fit for your research studies. Note- this resource is primarily for the quantitative designs in health care.