I was trying to figure out whether or not the distribution of a biomarker came from heterogeneous populations. Analyzing the data with
normalmixEM in the
mixtools package in R, I got two distributions, but the histogram was unimodal and seemed to be homogeneous. (Sorry, I cannot post an image because I'm new here.) So I conducted a chi-square test,
test.equality(y = biomarker), to see if it was from a homogeneous population but it gave a significant p-value following a warning of non-convergence. So my two related questions are:
- How do you normally figure out if the distribution is two-component instead of just one?
- Even if the analysis gives you two components, can the distribution still be from one population?