His writing can be dense and very heavy on the math and statistics, but this is why understanding what that data is actually saying is so important:

It is, for example, difficult to think of anything more unfair and destructive than closing schools, or even just labeling them as “failing,” when they are actually effective in serving the most disadvantaged student populations. But that’s exactly what’s happening in New York, and in a very high-profile manner, due in large part to misunderstanding of basic concepts of data interpretation and causal inference