The DAS has excellent reliability. Average internal consistency reliability coefficients for the GCA, based on the 13 whole-year age groups, are .90, .94, and .95 (Lower Preschool, Upper Preschool, and School-Age respectively), .88 for the Verbal Scales (Upper Preschool and School-Age), .89 and .90 for Preschool Nonverbal ability and School-Age Nonverbal Reasoning ability, and .92 for the Spatial ability scores.