While working on the final proposal, I find myself struggling to decide how big my sample size is appropriate for my project. If it is too big, it will be costly. If it is too small, the result will not be representative to the population. What complicate matters is that I must take into account the potential low response rate. According to Knight (2002), choosing sample size is really a judgment call, which depends on the population size, confidence level and confidence interval.
Do you guys have any input on this?
Knight, P.T. (2002). Small-Scale Research: Pragmatic Inquiry in Social Science and the Caring Professions. Thousand Oaks, CA: Sage.