Unlike the Raven's and NNAT, the ITBS is an achievement test designed to measure ".
Because the ITBS measures academic achievement and the NNAT and Raven's claim to measure nonverbal intelligence, it is not fair to compare these instruments apples to apples in the way that Lewis et al.
Instead, they chose to accept the test creators' claims of what their tests measured and didn't undertake to examine the technical manuals of either the NNAT or the ITBS.
The NNAT performs at least as well as the Raven's on comparisons with nonverbal intelligence and achievement.
2008) also compared NNAT scores with reading and mathematics composite scores on the TerraNova Test, which examines academic achievement.
Apparently, childhood ITBS scores are about as good of a measure of adult intelligence as childhood NNAT scores are of current intelligence.
The NNAT may be a useful tool in selecting for ethnically diverse students who may be gifted (Naglieri, 1996).
These studies were conducted on the MAT, not the revised NNAT.
Archival data on the Raven's, the NNAT, and each student's ethnicity was collected from an earlier study by Lewis (1999), along with archival scores from the Iowa Test of Basic Skills administered by the school district.
Students' scores on the Raven's, the NNAT, and the ITBS were compared to determine which assessment identified the greatest number of students in each cultural category at or above the 80th percentile level, this being the inclusive level used by Stephens et al.
The NNAT is divided into seven levels: Level A for Kindergarten, Level B for Grade 1, Level C for Grade 2, Level D for Grades 3-4, Level E for Grades 5-6, Level F for Grades 7, 8, 9, and Level G for Grades 10, 11, 12.