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<p>“An incredibly small fraction of a percent” of what? Of the reported SAT scores? I don’t think so, but I’d be happy to entertain counterarguments. </p>
<p>I think US News has created a completely false and potentiially highly misleading statistic here in the way it simply adds the reported 75th percent CR score to the reported 75th percentile M score to derive a phony “75th percentile CR+M” score that may bear no relation to reality. School 1 could have 100% overlap between its top 25% CR and top 25% M scores, in which case US News’ idiot method of simply adding the 75th percentile CR score to the 75th percentile M score would give you an accurate representation of the school’s 75th percentile CR+M. On the other hand, school 2 could have an entering class in which the CR scores of its top 25% M scorers were all 100 points below its 75th percentile CR score, and the M scores of its top 25% CR scorers were 100 points below its 75th percentile M score. Yet US News with its flawed “objective” methodology would show identical “75th percentile SAT CR+M scores” for the two schools. In the latter case, however, the school’s true 75th percentile CR+M score would be approximately 100 points below the true 75th percentile CR+M score for school 1, and approximately 100 points below the “75th percentile CR + M” score reported by US News—surely enough to drop the school a dozen or more places in the US News rankings, given that SAT/ACT scores count for 50% of the US News selectivity score, which in turn counts for a full 15% of the overall Us News score—one of the largest factors, and one that looms especially large in the minds of certain commentators (e.g., xiggi) who continue to hype “selectivity” as the quintessential measure of school quality. Turns out that for a lot of reasons, the US News-reported selectivity scores are pretty bogus, far from “objective,” and not measured in a statistically defensible fashion by US News.</p>
<p>Note also that schools that are into “gaming” the US News rankings—which I contend is a common practice—could easily “game” their reported CR+M numbers by choosing half the class primarily on the basis of high CR scores, and half the class on the basis of high M scores. The actual CR+M scores of their class might be lower than a school that sought more balance, but US News and its readers would be none the wiser.</p>