After creating the Stats Help page on the “Sobel Test Formula for Serial Mediation / Sequential Mediation,” hereby called serial mediation, I realized that an acceptable calculator did not exist to automatically calculate a sobel test for an entire serial mediation. Hayes’s PROCESS macro will calculate it in a simple
regression framework, but it does not allow for other methods to be used. So, I decided to quickly make one in excel. Click here for the calculator!
To use the calculator, just perform a regression of (1) X on M1, (2) X and M1 on M2, (3) and X, M1, and M2 on Y. Then, enter the relevant unstandardized beta coefficients and standard errors. The calculator will provide the sobel test results for the mediating effects of (1) M1 between X and Y, (2) M2 between X and Y, (3) M1 and M2 between X and Y together, and (4) their cumulative effect. So, results indicate the serial mediation of M1 and M2 between X and Y, as well as the
individual effects. Also, the calculator will provide the mediating effects of (5) M1 between X and M2 and (6) M2 between M1 and Y. These are less relevant to likely hypotheses of interest, but could still be informative.