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I think that’s reading more into the score range than is really there. In general, at selective colleges, the reported median range is roughly 100 points (for example, at Haverford it is 650-750 on each test; if you look at stats from less selective colleges, you still that on each test, the middle 50% falls within an 80-120 point range). I believe the standard deviation on the SAT is 110 points, and margin of error 60 points. So there really is no significant difference in scores at the 25th percent level and scores at the 75th percent level – they tend to all fall within one standard deviation.</p>
<p>Where data is available via the CDS, you can see that in general the students taken from the “bottom” 25% generally are not that much weaker than the 25th% level. That is, I’ve mentioned many times that my d’s scores put her at the bottom level – but, for example her college (Barnard) has a reported range of 630-730 CR, 620-710 math – she scored 620 CR, 580 math… that’s below the 25% mark, but not significantly below.</p>
<p>I think when statisticians are looking at the predictive aspects of the SAT they are looking at a broader range of scores – the median score range of all test-takers – where 500 is the median score. So there probably is a marked difference between students who score 400 (100 points below median) and students who score 600 (100 points above median).</p>
<p>But when you are looking at the predictive value of the scores for a kid who scores 550 vs. 750 … you are looking at a narrower range of ability, among students who by definition have above-average ability. The 400-600 range would cover student at at the 18th through 80th percentile on the CR test – so that is 62% of all test-takers. The 550-750 range covers students at the 67tn - 98th percentile – so that is a range that is only 31% of test takers, half the size of the range centered over the true median. </p>
<p>So you are going to see a much smaller “predictive” impact within that narrow band. I honestly believe that students who score at the 70th percentile or above are probably perfectly capable of performing well in any college environment, with the possible exception of a handful of particularly rigorous courses of study. </p>
<p>To add to that, in the the absence of a clearly identifiable hook, every kid with a low-end SAT score who is accepted to a selective college has some sort of counterweight – some reason that the ad com is choosing that kid despite weaker test score. Perhaps the applicant has very strong high school grades, or has complete a particularly rigorous high school curriculum; or perhaps the student is lopsided with particular academic abilities or other talents that make her attractive to the ad com. But any way you look at it, there is something that student has which compensates for the weaker scores. Most of the time, those compensating factors are probably things that mitigate against whatever predictive value the SAT score has. </p>
<p>In other words, a kid with a 550 SAT and a 3.2 GPA is not the same as a kid with a 550 SAT and a 4.0 GPA – and it gets kind of tricky when you are comparing a kid with a 550 SAT/4.0 GPA with a kid with a 750 SAT/3.2 GPA. </p>
<p>Bottom line: the college admissions committee has already decided that the kid is likely to do well enough at their college – otherwise they would not have admitted her. (“Well enough” because they can’t reasonably expect 100% of the student they admit to end up graduating in the top 10% ).</p>