STATA BOOTSTRAP CODE

The first statement performs the regression-based tests of a, b, direct effect, and total effect. The words in ALL CAPS are variable names.

STATA BOOTSTRAP CODE

After installing the sgmediation program from within Stata (using a findit sgmediation command from within Stata as described here), the following Stata code will perform a Preacher and Hayes test: sgmediation DEP_VAR, iv(INDEP_VAR) mv(MED_VAR)īootstrap r(ind_eff), reps(5000): sgmediation DEP_VAR, iv(INDEP_VAR) mv(MED_VAR) In essence, to replicate Preacher and Hayes, Stata should be programmed to do bootstrapping with case resampling and a percentile estimate of the confidence interval. What options and approaches should be taken to replicate the Preacher and Hayes test? However, as described here, a wide variety of Stata’s options and approaches to bootstrapping can be applied to sgmediation. In its basic form, sgmediation reports only the normal-based tests (e.g., Sobel), but Stata can be readily instructed to bootstrap the estimates.

How can an equivalent test be performed with Stata?Ī partial answer to the problem can be found in the sgmediation program, written by Philip Ender at UCLA. However, the Preacher and Hayes macros will only work with SPSS and SAS.

(2010), the Preacher and Hayes test is the most acceptable approach nowadays. A commonly cited solution is the bootstrapping method of Preacher and Hayes (2004) they provide SPSS and SAS macros that perform a bootstrapping test of the indirect effect. However, the statistical tests of the indirect effect described in Baron and Kenny (i.e., Sobel and its variants) are now known to be inappropriate. Regression-based tests of a, b, the direct effect, and the total effect are acceptable. The currently acceptable method is to directly test the total effect, direct effect, and indirect effect (i.e., mediated effect) of an independent variable. In this post, I provide Stata code for performing the Preacher and Hayes test.Īmong journal reviewers in my field, there was a time that the most accepted test for mediation was Baron and Kenny (1986). Those statistics packages are fine, but I prefer Stata. The well-known Preacher and Hayes macros for performing a bootstrapped test of mediation are designed to work only with SPSS or SAS.

Stata bootstrap