<p>this is a very interesting and insightful point and is probably right.
it is written by another cc poster in another thread. here it is:</p>
<p>Oftentimes, the ACT is taken by applicants who do not do satisfactorily on the SAT. Similarly, most applicants will elect to send their SAT scores over the ACT scores even if the scores concord similarly. Most admissions officers have a sense of this, and thus tend to view the ACT as somewhat of a fallback test for people, especially for those outside the midwest. </p>
<p>University of Illinois, for example, has the ACT as its informal "home field" test; the ACT is the predominant test in the midwest. If an applicant from Illinois, where taking the ACT is state-mandated, sends in only his or her SAT score, the admissions officers will wonder why the applicant resulted to taking the SAT over the ACT: "did the applicant do poorly and was forced to find a second metric?"</p>
<p>Similarly, Princeton's "home field" test is the SAT. Any benefit afforded for sending in SAT scores over ACT scores, however, is probably largely a product of mostly negligible and unconscious factors.</p>