title: SAS and SPSS macros to calculate standardized Cronbach's alpha using the upper bound of the phi coefficient for dichotomous items.
abstract: Cronbach's a 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 a 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 a for a scale with dichotomous items can be improved by using the upper bound of coefficient phi. SAS and SPSS macros have been developed in this article to obtain standardized Cronbach's a via this method. The simulation analysis showed that Cronbach's a from upper-bound phi might be appropriate for estimating the real reliability when standardized Cronbach's a is problematic.
authors.affiliation: University of Southern California, Los Angeles, California, USA. wsun@usc.edu
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.forename: Chih-Ping
authors.initials: CP
authors.lastname: Chou
authors.forename: Alan W
authors.initials: AW
authors.lastname: Stacy
authors.forename: Huiyan
authors.initials: H
authors.lastname: Ma
authors.forename: Jennifer
authors.initials: J
authors.lastname: Unger
authors.forename: Peggy
authors.initials: P
authors.lastname: Gallaher
mesh_terms: D003627:Data Interpretation, Statistical; D006801:Humans; D011584:Psychology / Q000379:methods* / Q000706:statistics & numerical data*