Distribution of the product confidence limits for the indirect effect: Program PRODCLIN
 David P. MacKinnon,
 Matthew S. Fritz,
 Jason Williams,
 Chondra M. Lockwood
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Abstract
This article describes a program, PRODCLIN (distribution of the PRODuct Confidence Limits for INdirect effects), written for SAS, SPSS, and R, that computes confidence limits for the product of two normal random variables. The program is important because it can be used to obtain more accurate confidence limits for the indirect effect, as demonstrated in several recent articles (MacKinnon, Lockwood, & Williams, 2004; Pituch, Whittaker, & Stapleton, 2005). Tests of the significance of and confidence limits for indirect effects based on the distribution of the product method have more accurate Type I error rates and more power than other, more commonly used tests. Values for the two paths involved in the indirect effect and their standard errors are entered in the PRODCLIN program, and distribution of the product confidence limits are computed. Several examples are used to illustrate the PRODCLIN program. The PRODCLIN programs in rich text format may be downloaded from www.psychonomic.org/archive.
 blah MacKinnonBRM2007.zip (6KB)
 Title
 Distribution of the product confidence limits for the indirect effect: Program PRODCLIN
 Journal

Behavior Research Methods
Volume 39, Issue 3 , pp 384389
 Cover Date
 20070801
 DOI
 10.3758/BF03193007
 Print ISSN
 1554351X
 Online ISSN
 15543528
 Publisher
 SpringerVerlag
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 Authors

 David P. MacKinnon ^{(1)}
 Matthew S. Fritz ^{(1)}
 Jason Williams ^{(2)}
 Chondra M. Lockwood ^{(1)}
 Author Affiliations

 1. Department of Psychology, Arizona State University, 852871104, Tempe, AZ
 2. Research Triangle Institute, Research Triangle Park, North Carolina