I worked for a few years in the department of a hospital that oversees all of the medical research going on there. I hate to say it, but that study is pretty typical of what passes for research. I've seen the same pattern repeated so many times I could scream, both in studies done at our hospital, and in study reports I read in medical journals. They go through records and enumerate certain data that they find. Then they enter the data into a statistical program (or have the statistician analyze it). They come up with correlations between the various data sets. They go on to conclude all sorts of things about the correlations that aren't supported by even the flimsiest shred of evidence. And the study gets published.
It doesn’t take much training in logic to see the incredible leaps from observed data to conclusions that many “studies” make. It’s annoying on FR sometimes, because there will be threads with 200 replies discussing some “research” result that’s the next thing to pure fiction.
“I met a guy in a bar who didn’t like blondes, and that proves an evolutionary disposition drink while looking at redheads.”