I am trying to do a moderated mediation in R using mediation package. My outcome variable W (wage quintiles) ordered and my mediator is binary. The moderator is binary G (gender). Treatment Elow is binary indicating low and high education But when testing the moderator using test.modmed, R gives the following error
Error in pval(z0.diff.sims[, i], d0.diff[i]) : object 'd0.diff' not found
How can I fix this error? How can I define do.diff in mediation analysis?
I tried the following code. Untill test.modmed function everything works well. But test.modmed results in an error
Error in pval(z0.diff.sims[, i], d0.diff[i]) : object 'd0.diff' not found
#mediator model--binary mediator (uses glm function)
med.mod.low <- glm(P ~ Elow*G + A + X, data = my_df,
family = binomial(link="probit"))
#outcome model--ordered mediator (uses polr function)
out.mod.low <- polr(W ~ P + Elow*G + P*G + A + X, data=my_df,
method = "probit", Hess = TRUE)
moderated.med.low <- mediate(med.mod.low, out.mod.low, treat = "Elow",
mediator = "P", boot=TRUE, sims=2)
test.low<-test.modmed(moderated.med.low, covariates.1 = list(G=1),
covariates.2 = list(G=2),
sims = 100)
