Our district uses the NNAT and I've looked at it closely. In our district, it does short change some verbally GT kids that might not do well in a group setting. They've set the threshold quite low (93% I believe) to make sure they're identifying enough ELL and at risk students. And in doing so, they're overidentifying other demographics. If you hit 93%, you can apply to a GT magnet. Which really looks just like a decent, high achieving school. We applied. Despite ceiling the test and having a teacher that could confirm achievement well beyond grade level, my DS couldn't even get in. Getting in is by random lottery and not need. Most kids that get in are within a year of grade level work. One thing about our magnet - it does seem to work best for the visual/spatial learners. More verbally GT kids don't do as well there are more globally or VS kids.
This is the ONLY tool our district uses. The only way around it is to file a portfolio if you score above 88% on the NNAT, get teacher recommendations, and show achievement. Either you are GT or your not. They don't differentiate at all between MG, HG, PG (even though they certainly have many kids in all these categories every year. We are in a large urban district with a big GT population).
Anyway, I totally agree that ideally it would be multi tier as far as IDing. And IDing for level of accommodation need.
The NNAT also has a low ceiling. Although, for school district purposes, if you're hitting the ceiling, you are likely to need major accommodations from the average classroom. It's a very difficult thing! It would be very sad to miss a GT child that would otherwise not be IDed unless it's through school testing. My kid actually was IDed by the school test. We knew nothing about the GT world until we got those scores back and things started to fall into place.
