Monday, July 21, 2014

One-tailed or two-tailed P values in PLS-SEM?


Should P values associated with path coefficients, as well as with other coefficients such as weights and loadings, be one-tailed or two-tailed? This question is addressed through a publication recently released as a ScriptWarp Systems research report:

Kock, N. (2014). One-tailed or two-tailed P values in PLS-SEM? Laredo, TX: ScriptWarp Systems.

PDF file:

http://www.scriptwarp.com/warppls/pubs/Kock_2014_OneTwoTailedPLSSEM.pdf

Abstract:

Should P values associated with path coefficients, as well as with other coefficients such as weights and loadings, be one-tailed or two-tailed? This question is answered in the context of structural equation modeling employing the partial least squares method (PLS-SEM), based on an illustrative model of the effect of e-collaboration technology use on job performance. A one-tailed test is recommended if the coefficient is assumed to have a sign (positive or negative), which should be reflected in the hypothesis that refers to the corresponding association. If no assumptions are made about coefficient sign, a two-tailed test is recommended. These recommendations apply to many other statistical methods that employ P values; including path analyses in general, with or without latent variables, plus univariate and multivariate regression analyses.