Skew and internal consistency

• 成果类型: Article
• 署名作者: Greer, Tammy; Dunlap, William P.; Hunter, Samuel T.; Berman, Mitchell E.
• 署名单位: University of Southern Mississippi; Tulane University; University of Oklahoma System; University of Oklahoma - Norman
• 刊物名称: JOURNAL OF APPLIED PSYCHOLOGY
• ISSN/ISSBN: 0021-9010
• DOI: 10.1037/0021-9010.91.6.1351
• 发表日期: 2006
• 页码: 1351-1358
• 关键词: skew; internal consistency; Monte Carlo simulation

摘要

The effects of skew on the standardized item alpha were examined with Monte Carlo techniques. Alphas computed from normal variables were compared with alphas from lognormal variables, ranks, and skewed versus normal Likert-type variables. The extent and direction of skew were varied, as was the size of the population interitem correlation (rho), the number of items, and the number of categories for Likert-type variables. Because the average interitern correlation affects alpha and skew affects the average interitem correlation, the effect of skew on the average interitern correlation also was examined. Results indicated that skew decreased the average interitern correlation and produced small decreases in alpha that were largest when skew was large, rho was small, items were skewed in opposite directions, and there were fewer items.