The big problem to is how these studies, research or what ever come from. Come up with an idea, belief,want to make a point about it, do a bunch of research to justify your theory then the research becomes valid fact. Yes your research was slanted, discarded anything that disagreed with your theory but you proved your theory right. Right? Sounds like the story of the guy who hated his neighbor. Bumped into his neighbor one day with his bible in hand and proceeds to read from it to the neighbor. The bible says judos went out found a tree and hung himself. He turns to another page whih says. Go thou and do likewise. Turns to another page That says, What thou do do'est quickly. So many of these research's usually imply the same type of justification. Just my opinion.
Just depends where the study came from. If it came from a reputable, peer reviewed journal then you can be relatively assured the science is robust.