Psychometric Properties of the Intelligence Scale for Chinese Adults

Aims: The Intelligence Scale for Chinese Adults (ISCA) has been recently developed to address the pressing need from assessment of adult intelligence in China. The purpose of this study is to test its psychometric properties in order to facilitate its utilization.
Study Design: This is an analytic study.
Place and Duration of the Study: The data of study were collected from 22 provinces of China within 8 months.
Methodology: The standardization sample of the ISCA (n=2035) was adopted to validate the construct validity and to estimate the internal consistency reliability. A sample of 101 participants tested the scale twice with an interval of 14-28 days to estimate test-retest reliability. A sample of 55 adults tested both the ISCA and the Chinese version of WAIS- III for Taiwan (WAIS- III-CT) in counterbalance order to estimate the concurrent validity.
Results: Age-group showed significant effects on raw scores for every subtest (η2: 0.082-0.665). Educational levels had statistically significant influence on the age-corrected scaled scores, intelligence indices and full scale intelligence quotient. Effect sizes of educational levels on scaled scores of the subtests in the Crystallized Subscale (η2: 0.144-0.202) were obviously larger than those in the Fluid Subscale (η2: 0.054-0.128). Results from a series of confirmatory factor analyses indicated that every subtest was unidimensional and the hierarchical structure of the full scale was acceptable. The internal consistency reliability of each core subtest was above 0.90, so was that of the full scale. The test-retest reliability of the full scale intelligence quotient was 0.94. Performance on the ISCA was correlated significantly with that on the WAIS- III-CT (r=0.90).
Conclusions: The ISCA has satisfactory levels of validity. The full scale and its subtests have sufficient internal consistence reliability and test-rest reliability. The ISCA is both valid and reliable as an instrument for the assessment of adult intelligence in China.