Robust mediation test
Performs a robust mediation test according to the method proposed by Zu & Yuan (2010).
ZYmediate(x, y, med, nboot = 2000, alpha = 0.05, kappa = 0.05)
x |
vector with predictor values. |
y |
vector with response values. |
med |
vector with mediator values. |
nboot |
number of bootstrap samples. |
alpha |
alpha level. |
kappa |
the percent of cases to be controlled when robust method is used. |
ZYmediate returns an object of class "robmed" containing:
a.est |
effect of predictor on mediator) |
b.est |
effect of mediator on response (in multiple regression model which includes the predictor as well) |
ab.est |
indirect effect (mediation effect) |
CI.ab |
confidence interval mediation effect |
p.value |
p-value mediation test |
call |
function call |
Zu J., Yuan, K.-H. (2010). Local influence and robust procedures for mediation analysis. Multivariate Behavioral Research, 45, 1-44.
## Leerkes data: ## Y: Efficacy ## X: MatCare ## M: Esteem ## fitting robust mediator regressions require(MASS) summary(rlm(Efficacy ~ MatCare, data = Leerkes)) summary(rlm(Esteem ~ MatCare, data = Leerkes)) summary(rlm(Efficacy ~ MatCare + Esteem, data = Leerkes)) ## robust testing of mediating effect (indirect effect) with(Leerkes, ZYmediate(MatCare, Efficacy, Esteem))
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