I've posted this link previously, about low RIT growth in high-achieving/GT students:

https://www.nwea.org/content/uploads/2014/08/Data-Award-Karen-Rambo-Research-Brief_0.pdf

This is the abstract to the refereed journal article:

http://www.tandfonline.com/doi/abs/10.1080/00220671.2013.850398#.VW4TiE_BzRY


...pronounced like the long vowel and first letter of the alphabet...