I'm currently evaluating a factory and I'm trying to find out whether there is a connection between the valuation multiple and the number of cows (denominator). I've got a sample of similar new factories (nearly 40). I did a regression and R2 was somewhere near 0,4. However, in the graph I saw two different clusters - <1000 and >1000 cows. I did a regression on each and the results were R2 of nearly 0,02 and 0,04. Am I correct that these two samples belong to different populations (with different means and st.deviations) and that I can't analyse them as one? How can I prove it?
Thanks in advance!