I found some information on the EXPLORE in the book Developing Math Talent. It states that there has been a lot of research on the EXPLORE and that it is useful for placement in terms of math as the score range your child achieves indicates what concepts have been mastered and what the child is likely to be ready to study. My son will take his first EXPLORE test in Feb with NUMATS so I can't speak from experience, just what I've read.
My understanding of the NUMATS program is also that you recieve two reports, one from ACT that compares your child's scores to 8th graders and then another one from Northwestern CTD that details how your child scored compared to others in the same grade level who took the test. That report is also supposed to provide some recommendations for educational planning such as acceleration and other approaches to meet needs based on the test results. The CTD website lists benefits of participating in the testing here:
http://www.ctd.northwestern.edu/numats/program/benefits/Again, we will be participating in NUMATS for the first time in Feb 09, so I'm not speaking from experience. But, my personal experience has been that when advocating for our son's needs in the public school it was the out of level testing that made them notice his needs. My son has previously taken a ERB-CTP and then the SAT10 out of level tests. Both of those were effective tools to advocate for needs. I think out of level testing in general helps tremendously to show where your child is advanced. I think using tests that the school is familiar with helps even more.
