<p>It seems obvious to me that the basis for the concordance tables is flawed.</p>
<p>Those tables tend to peg the 99th-percentile SAT score to the 99th-percentile ACT score, the 80th-percentile SAT score to the 80th-percentile ACT score, etc. However, this equivalence only holds if you assume that the two pools of test takers have the exact same ability distribution, of which there is no evidence.</p>
<p>Like xiggi, I have noticed that posters on this board who’ve taken both tests tend to have ACT scores too high for their SAT scores more often than the opposite. I don’t know if this is actually a statistical trend, but the point brought up above about some states forcing all public school pupils to take the ACT may suggest it is. If it is, it would suggest more able students take the SAT than the ACT.</p>
<p>I think the only way to come up with a reliable concordance table, barring forcing every student in the country to take the SAT and the ACT, would be to look at the scores of the students who’ve taken both tests and see how they correlate. I don’t think ACT would want that to happen, however, because of the potential for embarrassment.</p>