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. 2017 Apr 29;5(2):18. doi: 10.3390/jintelligence5020018

Figure 1.

Figure 1

Test-retest reliability data gathered from 34 separate studies on common IQ tests (the Standford-Binet, the WISC, the WISC-R, the WAIS, and the WAIS-R) indicate a drastic increase in reliability with age, with less stable scores in childhood and early adolescence compared to late adulthood (a). The interval between testing was another correlate of stability, with a drop in reliability as interval increases (b). Adapted and reprinted with permission from John Wiley and Sons: Journal of Clinical Psychology [40] © (1989).