The ERB will give you some better indication of how they are doing depending on the type of school you are at. The school can get scores normed against nation norms - based on kids form random public schools at their grade level taking the test, then against suburban public schools - based on the schools in more well-to-do neighborhoods with a higher level of education and then finally, against Independent nation norms - which is against schools like Philips Exeter and other elite private schools that use this test. The scores will probably be in the 99% for the national norms, but as the normed groups get more defined, they will probably drop - it basically zooms in on the top scores and separates them out more. I find the most beneficial ones to look at at the scores against the independent schools because those are the most selective schools and therefore will give you a better idea of how your child compares to elite school scores.
I know there are people who will say that those schools are not all geared towards gt kids, and I agree, but in terms of a score that you have access to, this is a good one to see more in than the standard Iowa scores.
