# Compare two samples from same population taken at different times

I have two samples (both n > 1000) taken from the same population. The first sample is taken in one year, say at t0, and the the other sample is taken a year after, say at t1. There are different people in the different samples, i.e. I do not have two measurements from the same person at t0 and t1. How do I test whether some proportion in the population has changed from t0 to t1?

My initial thought was to do a chi-squared test for difference in proportion, but I am not sure whether this is valid when the two samples are not from two populations. I have also considered doing a one-way within groups ANOVA.

If you are comparing individuals as measured on time $t$ to individuals as measured on time $t+k$, then you are dealing with two samples, each taken from the different population. Population in statistics is simply a group of cases sharing some property of interest.