So I was measuring correlations in Boxscores of basketball players in the NBA.
3PA DRB -0.205499
I was trying to find some interesting correlations. This is a correlation between 3 point shots attempted (3PA) and defensive rebounds (DRB). It is something that is not correlated with the development of play. Players who take more 3 point shots are usually guards that rebound less. So I tried to account for this by stratifying. I divided the data into two groups (centers/forwards & guards).
These are the correlations between the two attributes for the groups. The correlations are smaller, but is it significant?
What I want to know is how can you statistically prove this type of effect?