R: Robust mediation test

ZYmediate {WRS2} | R Documentation

## Robust mediation test

### Description

Performs a robust mediation test according to the method proposed by Zu & Yuan (2010).

### Usage

    ZYmediate(x, y, med, nboot = 2000, alpha = 0.05, kappa = 0.05)

### Arguments

`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.

### Value

`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

### References

Zu J., Yuan, K.-H. (2010). Local influence and robust procedures for mediation analysis. Multivariate Behavioral Research, 45, 1-44.

### Examples

    ## 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))

[Package WRS2 version 0.9-2 Index]