I would like to perform a moderation analysis after Propensity Score Matching with a binary outcome model. I estimate a logistic regression outcome model (following the this vignette). I am wondering, whether the hypothesis test I perform (hypothesis = "pairwise") to compare the subgroup ATTs is the correct specification when using a logistic regression model and Risk Ratios.
match_data_exact <- matchit (treatment ~ age +kids,
data = data_psm,
exact = ~ male,
method = "full", distance = "glm", tol = 1e-7)
md <- match.data(match_data_exact)
fit_car <- glm(car_often ~ treatment * male , md, weights = weights, family = quasibinomial())
#Compute effects; RR and confidence interval
comp_car <- avg_comparisons(fit_car,
variables = "treatment",
vcov = ~subclass,
newdata = subset(md, treatment == 1),
wts = "weights",
comparison = "lnratioavg",
transform = "exp",
by = "male")
summary(comp_car)
Term Contrast male Estimate Pr(\>|z|) 2.5 % 97.5 %.
treatment ln(mean(1) / mean(0)) 1 0.786 0.0641 0.609 1.014.
treatment ln(mean(1) / mean(0)) 0 0.729 0.0120 0.569 0.933.
Columns: term, contrast, male, estimate, p.value, conf.low, conf.high
comp_car_hypothesis <- avg_comparisons(fit_car,
variables = "treatment",
vcov = ~subclass,
newdata = subset(md, treatment == 1),
wts = "weights",
comparison = "lnratioavg",
transform = "exp",
by = "male",
hypothesis = "pairwise")
summary(comp_car_hypothesis)
Term Estimate Pr(\>|z|) 2.5 % 97.5 %.
1 - 0 1.08 0.623 0.798 1.46.
Columns: term, estimate, p.value, conf.low, conf.high