Description Usage Arguments Value References See Also Examples
sens
implements a set of bias formulas detailed in Zhou and Yamamoto (2020) for assessing
the sensitivity of estimated path-specific effects to an unobserved confounder U of a mediator-outcome
relationship. The user provides a fitted paths
object, the mediator whose relationship
with the outcome is potentially confounded, the estimand whose sensitivity to unobserved
confounding is being investigated, type of estimator, type of decomposition, and possible values of
the γ and η parameters.
1 2 3 4 5 6 7 8 9 |
object |
a fitted model object returned by the |
confounded |
a character string indicating the mediator whose relationship with the outcome
is potentially confounded. One of { |
estimand |
a character string indicating the estimand whose sensitivity to unobserved
confounding is being investigated. One of { |
estimator |
type of estimator, the pure imputation estimator ( |
decomp |
type of decomposition, |
gamma_values |
potential values of the γ parameter, which denotes the average effect of the unobserved confounder U on the outcome given pretreatment covariates X, treatment A, and mediators M_1,…, M_k. If not provided, it is defaulted to a range of 20 values from -\textup{sd}(Y) to \textup{sd}(Y), where sd denotes standard deviation and Y denotes the outcome variable. |
eta_values |
potential values of the η parameter, which denotes the difference in the prevalence of the unobserved confounder U between treated and untreated units given pretreatment covariates X and mediators M_1,…, M_k. If not provided, it is defaulted to a range of 20 values from -sd(A) to sd(A), where sd denotes standard deviation and A denotes the treatment variable. |
A list containing the following elements
original estimate of the corresponding path-specific effect.
a data frame where each row represents a potential combination of γ and η, the corresponding bias, bias-adjusted estimate, and an indicator for whether the bias-adjusted estimate is of the opposite sign to the original estimate.
Zhou, Xiang and Teppei Yamamoto. 2020. "Tracing Causal Paths from Experimental and Observational Data".
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | data(tatar)
m1 <- c("trust_g1", "victim_g1", "fear_g1")
m2 <- c("trust_g2", "victim_g2", "fear_g2")
m3 <- c("trust_g3", "victim_g3", "fear_g3")
mediators <- list(m1, m2, m3)
formula_m0 <- annex ~ kulak + prosoviet_pre + religiosity_pre + land_pre +
orchard_pre + animals_pre + carriage_pre + otherprop_pre + violence
formula_m1 <- update(formula_m0, ~ . + trust_g1 + victim_g1 + fear_g1)
formula_m2 <- update(formula_m1, ~ . + trust_g2 + victim_g2 + fear_g2)
formula_m3 <- update(formula_m2, ~ . + trust_g3 + victim_g3 + fear_g3)
formula_ps <- violence ~ kulak + prosoviet_pre + religiosity_pre +
land_pre + orchard_pre + animals_pre + carriage_pre + otherprop_pre
####################################################
# Causal Paths Analysis using GLM
####################################################
# outcome models
glm_m0 <- glm(formula_m0, family = binomial("logit"), data = tatar)
glm_m1 <- glm(formula_m1, family = binomial("logit"), data = tatar)
glm_m2 <- glm(formula_m2, family = binomial("logit"), data = tatar)
glm_m3 <- glm(formula_m3, family = binomial("logit"), data = tatar)
glm_ymodels <- list(glm_m0, glm_m1, glm_m2, glm_m3)
# propensity score model
glm_ps <- glm(formula_ps, family = binomial("logit"), data = tatar)
# causal paths analysis using glm
# note: For illustration purposes only a small number of bootstrap replicates are used
paths_glm <- paths(a = "violence", y = "annex", m = mediators,
glm_ymodels, ps_model = glm_ps, data = tatar, nboot = 3)
# sensitivity analysis for the path-specific effect via M1
sens_glm <- sens(paths_glm, confounded = "M1", estimand = "via M1",
gamma_values = - seq(0, 0.5, 0.005), eta_values = seq(-0.5, 0.5, 0.005))
plot(sens_glm)
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