Naglieri Nonverbal Ability Test

Versions and Standardization

There are two versions of the NNAT2; one uses a traditional paper-and-pencil method and the other is presented and scored online. Both versions consist of seven separate sets of items organized into levels corresponding to different grades. Each set is made up of 48 items that are presented in the colors black, blue, white, and yellow (these colors are least influenced by color-impaired vision). Each level contains items shared from both the adjacent higher and lower levels, as well as exclusive items. The shared items were used to develop a continuous scaled score across the entire standardization sample. These items yield a total raw score that is converted to a Nonverbal Ability Index standard score set at a mean of 100 with a standard deviation of 16 through an intermediate value called a Scaled Score.

The NNAT was standardized on a large nationally representative sample of more than 33,000 students in Grades K through 12 (ages 5 through 18 years). The sample closely matches the U.S. population on the basis of geographic region, socioeconomic status, urbanicity, ethnicity, and school setting. The sample included children with special needs such as those with emotional disturbance, learning disabilities, hearing and visual impairment, and those who were mentally handicapped. Children with limited English proficiency were also included in the standardization sample. More details may be obtained from the NNAT2 Technical Manual.

Validity

The validity of the NNAT has been examined in a series of published research papers. Jack Naglieri and Margaret Ronning studied mean score differences and correlations to achievement for matched samples of White (n = 2,306) and African American (n = 2,306); White (n = 1,176) and Hispanic (n = 1,176); and White (n = 466) and Asian (n = 466) students in Grades K through 12. The three pairs of groups were carefully selected from a larger sample included in the NNAT standardization sample and matched on all demographic variables.

Figure 1 Illustrative Naglieri Nonverbal Ability Test–Second Edition item

Only small differences were found between the NNAT scores for the White and African American samples (Cohen's d ratio = .25), White and Hispanic (d ratio = .17), and White and Asian (d ratio = .02) groups. In addition, the correlations between NNAT and academic achievement were strong and consistent across Grades K through 12 and similar for each of the samples. The small mean score differences and the strong correlations strongly suggest that the NNAT has utility for fair assessment of minority children and that the scores the test yields are good for statistical prediction of achievement.

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