Are We Overestimating IQ Reliability? Inconsistent Intraindividual Comparability of Screening IQ and Full-Scale IQ for Three Different Test Batteries.

Individual-level comparability and validity of Screening IQ versus Full-Scale (FS)IQ were investigated for three intelligence test batteries. Individual 95% confidence intervals overlapped for 57.6% to 97.9% of participants. Age and IQ predicted some of the IQ differences and FSIQ showed incremental validity for scholastic achievement for two test batteries.