CogAT is an ability test rather than achievement, so by using a matrix of achievement and ability, it sounds similar to other schools. The idea in our district (using another standardized assessment, not STAR) is to broaden the pool, catching a lower-achieving high-ability kid, or a high-achiever who doesn't test well on the CogAT, along with one who does well on both. Still can miss those who don't test well on those.