Reliability & Comparisons
Methods used to estimate reliability included split-half method, test-retest reliability, and interscorer agreement. The coefficients for the subtests were determined using the split-half method. The scores were rectified with the Spearman-Brown formula. Nonverbal subtests reliability coefficients averaged between .85 and .89. Verbal subtests reliability coefficients were strong and fell between .84 and .89. (Johnson & D’Amato, 2004)
“Reliability for the IQ and Factor Index scores was computed using ‘the formula for a reliability of a sum of multiple tests’ (technical manual, p.63)." (Johnson & D’Amato, 2004) The Full Scale IQ average reliability coefficients was .98, Nonverbal IQ average reliability coefficients was .95, Verbal IQ average reliability coefficients was .96, and the Abbreviated Battery IQ average reliability coefficients was .91. The Factor Index scores had included Fluid Reasoning at .90, Knowledge at .92, Quantitative Reasoning at .92, Visual-Spatial Processing at .92, and Working Memory at .91. (Johnson & D’Amato, 2004)
Throughout all of the age levels, standard errors of measurement were discovered. Full Scale IQ standard error of measurement was 2.30, Nonverbal IQ standard error of measurement was 3.26, and Verbal IQ standard error of measurement was 3.05. Correlations ranged from .74 to .97 for interscorer agreement reliability. This data shows sufficient interscorer agreement. (Kush, 2004)
The technical manual for the Stanford Binet details a study involving 104 participants who took both the Fifth Edition and the Fourth Edition. A strong criterion-related validity was found with Full Scale scores averaging .90. The Fifth Edition average Full Scale score was lower than the Fourth Edition average Mean Composite score. (SB5=107.9, SB4 = 111.4). These results are found to be consistent with the Flynn Effect. (Kush, 2004)
Studies which compared the Stanford Binet Intelligence Scale Fifth Edition with Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R) (r = .83); the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) (r = .84); the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) (r = .82); and the Woodcock-Johnson III Tests of Cognitive Abilities (r = .78) found supplementary criterion-related validity. (Kush, 2004)
So how does the Stanford-Binet compare to the Otis Lennon School Ability Test? In Part 3 of our articles we will look at what the Otis-Lennon School Ability Test is and how you can get it!