Title

SAS and SPSS Macros to Calculate Standardized Cronbach’s Alpha Using the Upper Bound of the Phi Coefficient for Dichotomous Items

Document Type

Article

Department

Community and Global Health (CGU)

Publication Date

2-2007

Disciplines

Psychology | Social and Behavioral Sciences

Abstract

Cronbach’s α is widely used in social science research to estimate the internal consistency of reliability of a measurement scale. However, when items are not strictly parallel, the Cronbach’s α coefficient provides a lower-bound estimate of true reliability, and this estimate may be further biased downward when items are dichotomous. The estimation of standardized Cronbach’s α for a scale with dichotomous items can be improved by using the upper bound of coefficient ϕ. SAS and SPSS macros have been developed in this article to obtain standardized Cronbach’s α via this method. The simulation analysis showed that Cronbach’s α from upper-bound ϕ might be appropriate for estimating the real reliability when standardized Cronbach’s α is problematic.

Rights Information

© 2007 Psychonomic Society, Inc.