Estimate Sobel's (1982) Test for Mediation
Estimate Sobel's (1982) indirect test for mediation. The function provides an estimate of the magnitude of the indirect effect, Sobel's first-order estimate of the standard error associated with the indirect effect, and the corresponding z-value. The estimates are based upon three models as detailed on page 84 of MacKinnon, Lockwood, Hoffman, West and Sheets (2002).
- The predictor or independent variable (X).
- The mediating variable (M).
- The outcome or dependent variable (Y).
MacKinnon, D. P., Lockwood, C. M., Hoffman, J. M., West, S. G., Sheets, V. (2002). A comparison of methods to test mediation and other intervening variable effects. Psychological Methods, 7, 83-104.
Sobel, M. E., (1982). Asymptotic confidence intervals for indirect effects in structural equation models. In S. Leinhardt (Ed.), Sociological Methodology 1982 (pp. 290-312). Washington, DC: American Sociological Association.
data(bh1996) #A small but significant indirect effect indicates leadership mediates #the relationship between work hours and well-being. sobel(pred=bh1996$HRS,med=bh1996$LEAD,out=bh1996$WBEING)