I have a sample of 9 patients. If I evaluate the correlation with the Spearman's test between some variables I measured in time 0 and then I repeat the same test with the same variables in time 1, is it normal that the results of "significant correlation" change?
In particular I find several significant correlation in the pre treatment, and just one significant correlation in the post, with p=0.038, which however was not significant in the other phase. What does imply the fact that all these variable are correlated in the pre and not in the post?
Should I instead perform a correlation test with all the values in a single vector, without considering pre and post phases?