> evaluated according to a standard research measure that notes, for instance, the number of books that researchers observed in the home and how responsive mothers were to their children in the researchers’ presence

Number of books? Seriously? This is the stupidest...

Almost all the books in my childhood home belonged to me. My parents and one of my brothers never read for fun, and and my other brother only rarely. One of my friends was similar, his siblings didn't read almost at all (though I think he got most of his books from the library, so there were few in the house).

Counting just the number of books tells you almost nothing about any given individual family member.

Someone, please, tell me this journalist is incorrectly simplifying the actual standard practice...