Item Instability on the Piers-Harris Children's Self-Concept Scale for Academic Underachievers with High,Middle,and Low Self-Concepts: Implications for Construct Validity

Test-retest item instability indices for low, middle, and high scorers on the Piers-Harris Children's Self-Concept Scale were calculated in order to test Wylie's (1974) hypothesis that low scores are invalid because of unreliability of responding. Academic underachievers served as subjects, and the results failed to support Wylie's prediction. Children with high self-concept scores exhibited significantly less item instability than did children with either middle- or low-self-concept scores, while the latter two groups did not differ on the item stability variable. The obtained results were discussed in terms of age-progressive self-concept "crystallization."