Significance of Mediation (Sobel Test) Formulas

Significance of Mediation (Sobel Test) Formulas

Below you will find descriptions and details for the 3 formulas that are used to compute Sobel tests for the significance of meditation.

Cumulative distribution function (CDF) for the normal distribution:

Variable definitions:
µ = mean
σ = standard deviation
erf = error function

Error function:

Sobel test statistic:

Variable definitions:
a = regression coefficient for the relationship between the independent variable and the mediator
b = regression coefficient for the relationship between the mediator and the dependent variable
SE_a = standard error of the relationship between the independent variable and the mediator
SE_b = standard error of the relationship between the mediator variable and the dependent variable