Nothing
##' This function calculates scalar weights for use in other models
##'
##' This function calculates the scalar weights
##'
##'
##' @param treat is the name of the treatment variable contained in
##' \code{data}.
##' @param treat_formula an object of class "formula" (or one that can be
##' coerced to that class) that regresses \code{treat} on a linear combination
##' of \code{X}: a symbolic description of the model to be fitted.
##' @param numerator_formula an object of class "formula" (or one that can be
##' coerced to that class) that regresses \code{treat} on a linear combination
##' of \code{X}: a symbolic description of the model to be fitted. i.e.
##' \code{treat ~ 1}.
##' @param data is a dataframe containing \code{treat}, and
##' \code{X}.
##' @param treat_mod a description of the error distribution to be used in the
##' model for treatment. Options include: \code{"Normal"} for normal model,
##' \code{"LogNormal"} for lognormal model, \code{"Poisson"} for Poisson model,
##' \code{"Sqrt"} for square-root transformation
##' to a normal treatment,
##' \code{"NegBinom"} for negative binomial model, \code{"Gamma"} for gamma
##' model.
##' @param link_function is either "log", "inverse", or "identity" for the
##' "Gamma" \code{treat_mod}.
##' @param ... additional arguments to be passed to the treatment regression fitting function.
##'
##' @return \code{scalar_wts} returns an object of class "causaldrf_wts",
##' a list that contains the following components:
##'
##' \item{param}{summary of estimated weights.}
##' \item{t_mod}{the result of the treatment model fit.}
##' \item{num_mod}{the result of the numerator model fit.}
##' \item{weights}{estimated weights for each unit.}
##' \item{call}{the matched call.}
##'
##' @seealso \code{\link{iptw_est}}, \code{\link{ismw_est}},
##' \code{\link{reg_est}}, \code{\link{aipwee_est}}, \code{\link{wtrg_est}},
##' etc. for other estimates.
##'
##' \code{\link{t_mod}}, \code{\link{overlap_fun}} to prepare the \code{data}
##' for use in the different estimates.
##'
##' @references Schafer, J.L., Galagate, D.L. (2015). Causal inference with a
##' continuous treatment and outcome: alternative estimators for parametric
##' dose-response models. \emph{Manuscript in preparation}.
##'
##' @examples
##'
##' ## Example from Schafer (2015).
##'
##' example_data <- sim_data
##'
##' scalar_wts_list <- scalar_wts(treat = T,
##' treat_formula = T ~ B.1 + B.2 + B.3 + B.4 + B.5 + B.6 + B.7 + B.8,
##' numerator_formula = T ~ 1,
##' data = example_data,
##' treat_mod = "Normal")
##'
##' sample_index <- sample(1:1000, 100)
##'
##' plot(example_data$T[sample_index],
##' scalar_wts_list$weights[sample_index],
##' xlab = "T",
##' ylab = "weights",
##' main = "scalar_wts")
##'
##'
##' rm(example_data, scalar_wts_list, sample_index)
##'
##'
##' @export
##'
##'
##' @usage
##'
##' scalar_wts(treat,
##' treat_formula,
##' numerator_formula,
##' data,
##' treat_mod,
##' link_function,
##' ...)
##'
scalar_wts <- function(treat,
treat_formula,
numerator_formula,
data,
treat_mod,
link_function,
...){
# treat is the name of the treatment variable
# treat_formula is the formula for the covariates model of the form: ~ X.1 + ....
# numerator_formula is the formula for the numerator of the weights of the form: ~ X.1 + .... or ~ 1
# data will contain all the data: X, treat
# treat_mod is th treatment model to fit
# link_function is the link function used, if needed
# The outcome is the estimated parameters.
#save input
tempcall <- match.call()
#some basic input checks
if (!("treat" %in% names(tempcall))) stop("No treat variable specified")
if (!("treat_formula" %in% names(tempcall))) stop("No treat_formula model specified")
if (!("numerator_formula" %in% names(tempcall))) stop("No numerator_formula model specified")
if (!("data" %in% names(tempcall))) stop("No data specified")
if (!("treat_mod" %in% names(tempcall)) | ("treat_mod" %in% names(tempcall) & !(tempcall$treat_mod %in% c("NegBinom", "Poisson", "Gamma", "LogNormal", "Sqrt", "Normal")))) stop("No valid family specified (\"NegBinom\", \"Poisson\", \"Gamma\", \"Log\", \"Sqrt\", \"Normal\")")
if (tempcall$treat_mod == "Gamma") {if(!(tempcall$link_function %in% c("log", "inverse"))) stop("No valid link function specified for family = Gamma (\"log\", \"inverse\")")}
if (tempcall$treat_mod == "NegBinom") {if(!(tempcall$link_function %in% c("log", "inverse"))) stop("No valid link function specified for family = NegBinom (\"log\", \"inverse\")")}
if (tempcall$treat_mod == "binomial") {if(!(tempcall$link_function %in% c("logit", "probit", "cauchit", "log", "cloglog"))) stop("No valid link function specified for family = binomial (\"logit\", \"probit\", \"cauchit\", \"log\", \"cloglog\")")}
if (tempcall$treat_mod == "ordinal" ) {if(!(tempcall$link_function %in% c("logit", "probit", "cauchit", "cloglog"))) stop("No valid link function specified for family = ordinal (\"logit\", \"probit\", \"cauchit\", \"cloglog\")")}
#make new dataframe for newly computed variables, to prevent variable name conflicts
tempdat <- data.frame(
treat = data[,as.character(tempcall$treat)]
)
formula_t <- tempcall$treat_formula
formula_numerator = tempcall$numerator_formula
samp <- data
if (treat_mod == "Poisson"){
result <- glm(formula_t,
family = "poisson",
data = samp,
...)
cond_mean <- result$fitted.values
samp$gps_vals <- dpois(x = tempdat$treat,
lambda = cond_mean)
# calculate numerator of the weight
num_mod <- glm(formula_numerator,
family = "poisson",
data = samp,
...)
cond_mean_num <- num_mod$fitted.values
samp$num_weight <- dpois(x = tempdat$treat,
lambda = cond_mean_num)
# weights
est_import_wt <- samp$num_weight/samp$gps_vals
} else if (treat_mod == "NegBinom"){
result <- MASS::glm.nb(formula_t,
link = link_function,
data = samp,
...)
cond_mean <- result$fitted.values
cond_var <- cond_mean + cond_mean^2/result$theta
prob_nb_est <- (cond_var - cond_mean) / cond_var
samp$gps_vals <- dnbinom(x = tempdat$treat,
size = result$theta,
mu = result$fitted.values,
log = FALSE)
# calculate numerator of the weight
num_mod <- MASS::glm.nb(formula_numerator,
link = link_function,
data = samp,
...)
cond_mean_num <- num_mod$fitted.values
cond_var_num <- cond_mean_num + cond_mean_num^2/num_mod$theta
prob_nb_est_num <- (cond_var_num - cond_mean_num) / cond_var_num
samp$num_weight <- dnbinom(x = tempdat$treat,
size = num_mod$theta,
prob = prob_nb_est_num,
mu = num_mod$fitted.values,
log = FALSE)
# weights
est_import_wt <- samp$num_weight/samp$gps_vals
} else if (treat_mod == "Gamma"){
result <- glm(formula_t,
family = Gamma(link = link_function),
data = samp,
...)
shape_gamma <- as.numeric(MASS::gamma.shape(result)[1])
theta_given_X <- result$fitted.values/shape_gamma
samp$gps_vals <- dgamma(tempdat$treat,
shape = shape_gamma,
scale = theta_given_X)
# calculate numerator of the weight
num_mod <- glm(formula_numerator,
family = Gamma(link = "log"),
data = samp,
...)
shape_gamma_2 <- as.numeric(MASS::gamma.shape(num_mod)[1])
theta_given_X_2 <- num_mod$fitted.values/shape_gamma
samp$num_weight <- dgamma(tempdat$treat,
shape = shape_gamma_2,
scale = theta_given_X_2)
# weights
est_import_wt <- samp$num_weight/samp$gps_vals
} else if (treat_mod == "LogNormal"){
samp[, as.character(tempcall$treat)] <- log(samp[, as.character(tempcall$treat)])
result <- lm(formula_t,
data = samp,
...)
samp$gps_vals <- dnorm(samp[, as.character(tempcall$treat)],
mean = result$fitted,
sd = summary(result)$sigma )
num_mod <- lm(formula_numerator,
data = samp,
...)
samp$num_weight <- dnorm(samp[, as.character(tempcall$treat)],
mean = coef(num_mod)[1],
sd = summary(num_mod)$sigma )
est_import_wt <- samp$num_weight/samp$gps_vals
} else if (treat_mod == "Sqrt"){
samp[, as.character(tempcall$treat)] <- sqrt(samp[, as.character(tempcall$treat)])
result <- lm(formula_t,
data = samp,
...)
samp$gps_vals <- dnorm(samp[, as.character(tempcall$treat)],
mean = result$fitted,
sd = summary(result)$sigma )
num_mod <- lm(formula_numerator,
data = samp,
...)
samp$num_weight <- dnorm(samp[, as.character(tempcall$treat)],
mean = coef(num_mod)[1],
sd = summary(num_mod)$sigma )
est_import_wt <- samp$num_weight/samp$gps_vals
} else if (treat_mod == "Normal"){
result <- lm(formula_t,
data = samp,
...)
samp$gps_vals <- dnorm(tempdat$treat,
mean = result$fitted,
sd = summary(result)$sigma )
num_mod <- lm(formula_numerator,
data = samp,
...)
samp$num_weight <- dnorm(tempdat$treat,
mean = coef(num_mod)[1],
sd = summary(num_mod)$sigma )
est_import_wt <- samp$num_weight/samp$gps_vals
} else {
stop("Error: treat_mod not recognized!!!")
}
z_object <- list(params = summary(est_import_wt),
t_mod = result,
num_mod = num_mod,
weights = est_import_wt,
call = tempcall)
class(z_object) <- "causaldrf_wts"
z_object
}
##' @export
summary.causaldrf_wts <- function(object,...){
cat("\nSummary values:\n")
print(object$param)
cat("\nTreatment Summary:\n")
print(summary(object$t_mod))
cat("\nNumerator Summary:\n")
print(summary(object$num_mod))
}
##' @export
print.summary.causaldrf_wts <- function(x, ...){
cat("\nTreatment Summary:\n")
print(summary(x$t_mod))
cat("\nNumerator Summary:\n")
print(summary(x$num_mod))
}
##' @export
print.causaldrf_wts <- function(x,...){
# cat("Call:\n")
# print(x$call)
cat("\nEstimated values:\n")
print(x$param)
}
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