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<p>I agree with this, but only because the group of students who scored 800 includes those whose abilities are well beyond the capability of the SAT to distinguishably measure.</p>
<p>In general (away from the end points of the scale), a score range of ± 30 points is pretty typical, according to the CB. For example, a score of 650 would typically result in a score range of 620-680. A score difference of 20 points (e.g., 640 vs 660) between two people in this context is not significant.</p>