Again such a useless "correlation study".
Correllation studies are statistical collectioner passtimes, on usually at random A & B's
Correllation studies are NOT causal relationship studies.
They are done for the sole sake of getting funding for institutes, because fundgivers want to see numbers of papers as proof their money is well used... scientific respectability is not amongst their priorities.
Correllation studies are : CHEAP, DIRECTIONLESS, NON-CAUSAL, EASY TO DROP OFF ON STUDENTS
I'm very happy that in most European universities, students get sacked if they deliver a correllation study and dare to say they found something ...