We have a bi-annual survey and an intended sample size of 1,300. This sample size was determined using Krejcie's means formula for finite populations, and we drew the sample using 2-stage clustering. The data collected is primarily income, the population is quite stable and known (people in a certain industry in a particular area). This is a panel survey, so the same sample of 1,300 will be surveyed every year to directly compare changes in their income.
I have been asked to calculate the power of our sample. I have a basic understanding of what power is, and that you can either calculate the sample size taking into account the power you want, or you can perform an post-hoc power analysis. I know that it is the probability that the test correctly rejects the null hypothesis (H0) when the alternative hypothesis (H1) is true. How, then, do I perform a power analysis of the sample we currently have?