Problem:
In summary, this meta-analysis of longitudinal studies showed that cognitive abilities exhibit high rank order stability, reaching its peak around age 20 and remaining at this high level throughout adulthood and old age. Mean stability estimate for age 20 and a test-retest-interval of five years were ρ = .77 for the observed correlations and ρ = .86 for the disattenuated correlations. Stability is much lower in young children. Before age 4, stability never exceeds .70, whereas in late adolescence, the stability no longer drops below this value for any test-retest interval. The low stability in young children cannot be explained by lower test reliability in this age group; overall, the correlation between test reliability and mean sample age is low. General intelligence and knowledge-based abilities were found to be somewhat more stable than abilities based on effortful processing (ρ = .77-.80 vs. ρ = .65-.75 for an age of 20 and an interval of 5 years). Reliability differences between tests of knowledge-based and effortful processing-based abilities in part account for the tests' differences in stability. Multidimensional intelligence tests may generally be preferred over unidimensional tests when the goal is a high stability of the test result, especially when there is no specific need for assessing individual ability domains. Our findings indicate that the use of cognitive testing in diagnostic decision making in younger children in particular may require repetition. Need Assignment Help?