`mediation()`

is a short summary for multivariate-response
mediation-models, i.e. this function computes average direct and average
causal mediation effects of multivariate response models.

mediation(model, ...) # S3 method for brmsfit mediation( model, treatment, mediator, response = NULL, centrality = "median", ci = 0.95, method = "ETI", ... ) # S3 method for stanmvreg mediation( model, treatment, mediator, response = NULL, centrality = "median", ci = 0.95, method = "ETI", ... )

model | A |
---|---|

... | Not used. |

treatment | Character, name of the treatment variable (or direct effect)
in a (multivariate response) mediator-model. If missing, |

mediator | Character, name of the mediator variable in a (multivariate
response) mediator-model. If missing, |

response | A named character vector, indicating the names of the response
variables to be used for the mediation analysis. Usually can be |

centrality | The point-estimates (centrality indices) to compute. Character (vector) or list with one or more of these options: |

ci | Value or vector of probability of the CI (between 0 and 1)
to be estimated. Default to |

method |

A data frame with direct, indirect, mediator and
total effect of a multivariate-response mediation-model, as well as the
proportion mediated. The effect sizes are median values of the posterior
samples (use `centrality`

for other centrality indices).

`mediation()`

returns a data frame with information on the
*direct effect* (mean value of posterior samples from `treatment`

of the outcome model), *mediator effect* (mean value of posterior
samples from `mediator`

of the outcome model), *indirect effect*
(mean value of the multiplication of the posterior samples from
`mediator`

of the outcome model and the posterior samples from
`treatment`

of the mediation model) and the total effect (mean
value of sums of posterior samples used for the direct and indirect
effect). The *proportion mediated* is the indirect effect divided
by the total effect.

For all values, the 89% credible intervals are calculated by default.
Use `ci`

to calculate a different interval.

The arguments `treatment`

and `mediator`

do not necessarily
need to be specified. If missing, `mediation()`

tries to find the
treatment and mediator variable automatically. If this does not work,
specify these variables.

The direct effect is also called *average direct effect* (ADE),
the indirect effect is also called *average causal mediation effects*
(ACME). See also Tingley et al. 2014 and Imai et al. 2010.

There is an `as.data.frame()`

method that returns the posterior
samples of the effects, which can be used for further processing in the
different bayestestR package.

Imai, K., Keele, L. and Tingley, D. (2010) A General Approach to Causal Mediation Analysis, Psychological Methods, Vol. 15, No. 4 (December), pp. 309-334.

Tingley, D., Yamamoto, T., Hirose, K., Imai, K. and Keele, L. (2014). mediation: R package for Causal Mediation Analysis, Journal of Statistical Software, Vol. 59, No. 5, pp. 1-38.

The mediation package for a causal mediation analysis in the frequentist framework.

if (FALSE) { library(mediation) library(brms) library(rstanarm) # load sample data data(jobs) set.seed(123) # linear models, for mediation analysis b1 <- lm(job_seek ~ treat + econ_hard + sex + age, data = jobs) b2 <- lm(depress2 ~ treat + job_seek + econ_hard + sex + age, data = jobs) # mediation analysis, for comparison with Stan models m1 <- mediate(b1, b2, sims = 1000, treat = "treat", mediator = "job_seek") # Fit Bayesian mediation model in brms f1 <- bf(job_seek ~ treat + econ_hard + sex + age) f2 <- bf(depress2 ~ treat + job_seek + econ_hard + sex + age) m2 <- brm(f1 + f2 + set_rescor(FALSE), data = jobs, cores = 4, refresh = 0) # Fit Bayesian mediation model in rstanarm m3 <- stan_mvmer( list( job_seek ~ treat + econ_hard + sex + age + (1 | occp), depress2 ~ treat + job_seek + econ_hard + sex + age + (1 | occp) ), data = jobs, cores = 4, refresh = 0 ) summary(m1) mediation(m2, centrality = "mean", ci = .95) mediation(m3, centrality = "mean", ci = .95) }