med_serial2: Serial Mediation Model with Two Mediators
In jeksterslabds/jeksterslabRds: Jekster's Lab Data Science and Statistics

Estimates the indirect effect in a serial mediation model, that is the product of α1, xi and β2 from M1_i = δ_{M1} + α1 X_i + ε_{M1_i}, M2_i = δ_{M2} + α2 X_i + ξ M1_i + ε_{M2_i}, and Y_i = δ_Y + τ^{\prime} X_i + β1 M1_i + β2 M2_i + ε_{Y_i}.

1	med_serial2(data, scale = FALSE, minimal = TRUE, s2 = FALSE, s2_est = "both")

`data`	A matrix with variables X, M1, M2, and Y.
`scale`	Logical. If `TRUE`, scales the data before fitting the model.
`minimal`	Logical. If `TRUE`, returns the indirect effect of X on Y through M1 and M2. If `FALSE`, returns all the regression coefficients estimated.
`s2`	Logical. If `TRUE`, estimates residual variance.
`s2_est`	String. Residual variance estimator. If `"both"`, returns both OLS and ML estimates as a vector. If `"ols"`, returns OLS estimate. If `"ml"`, returns ML estimate. Ignored if `s2 = FALSE`.