<p>
Actually, the underlying mathematical assumption is that the two candidates would have received an A+ at the same frequency.</p>
<p>In other words, if I get eight A’s and two A+'s, and somebody else gets ten A’s, if the LSAC treats us identically, then the LSAC is implicitly assuming that the other candidate would also have gotten 20% A+'s if only his school assigned them.</p>
<p>Furthermore, the LSAC loses information between candidates from similar-grading schools. Compare me (again, 8 A’s and 2 A+'s) to a student from my own school (10 A’s). We have performed differently, and for the LSAC to erase that discrepancy could be seen as unfair.</p>