Schools are divided into six categories: (i) «gaining ground schools» which have met standards but have only
minimal gain scores; (ii) volatile schools, whose
performance varies significantly from year to year and
criteria to
criteria; (iii) «national challenge schools», who meet neither the norm standards nor the gain score standards; (iv) «good to great schools» which do not meet norm
criteria but have high gain scores and (v) great schools which have high norm results and high gain scores.
Forward collision warning systems that meet
performance criteria set by the National Highway Traffic Safety Administration and autobrake systems that provide only
minimal speed reduction in IIHS tests earn a basic rating.