0.5 correlation means it is maybe perhaps correlated given Emax view of the statistics. For normal variates you should aim for R=0.95 at least. Both MBTI and Big Five are approximately normal variates.
Also correlation is a linear operator which is not particularly sensitive to anything nonlinear.
Use a good statistical test instead.
Also correlation is a linear operator which is not particularly sensitive to anything nonlinear. Use a good statistical test instead.