New York Review of Books: For decades, New York University education professor Diane Ravitch has written about, spoken about, and served US education, including as an official in the administration of President George H. W. Bush. In her NYRB commentary she bluntly condemns teacher-performance metrics based on scores from standardized tests. Framing her national argument in terms of current education politics in New York, she asserts that such tests “are not yardsticks” or “scientific instruments,” but instead “are social constructions, and quite apart from how contingent their results are on the social and economic background of the students being tested, they are also subject to human error, sampling error, random error, and other errors.” She also condemns common analogies: “It is true that the cleanliness of restaurants can be given a letter grade,” that “agribusiness can be measured by crop yields,” and that “corporations can be measured by their profits,” she writes. But “to apply a letter grade or a numerical ranking to a professional is to radically misunderstand the complex set of qualities that make someone good at what they do. It is an effort by economists and statisticians to quantify activities that are at heart matters of judgment, not productivity.”