No, this paper is a review of other studies, and what I'm saying is it finds that there are quite a few problems with the studies they're reviewing - they point

No, this paper is a review of other studies, and what I'm saying is it finds that there are quite a few problems with the studies they're reviewing - they point out that the smaller studies that show stronger results are actually less likely to be generalizable, and the studies that are broader show weaker results but even then they still have flaws in the method. There is quite a good table (figure 2) that shows how they rate their "concerns" for a number of metrics, and it's a sea of red where they have lots of concerns.