It is from a few years ago, so I'm not sure if all of these yarns are still available. I have never seen some of them, but that could be because they're not available where I live, either.
I found that pretty helpful as I make my kids hats out of cotton yarn. I really have noticed a big difference in them and I found it interesting that my least favorite, for making hats at least is Cotton Tots because it is too soft and the hats don't hold their shape, was the #1 pick in this study.