#code for Chapter 3 "Propensity Score Weighting" of book:
#Leite, W. L. (2017). Practical propensity score methods using R. 
#Thousand Oaks, CA: Sage. 
# 
#this is the code that was used to generate the example results in the book
#As the R software and the R packages used in this example are updated frequently
#some incompatibilities between the current code and new R versions or package versions
#may appear
#Any updates to the code will be posted at:
# http://www.practicalpropensityscore.com


#=====================================================
#obtain weights with propensity scores estimated with random forests

#load data
load(file="Chapter3_ELS_data_imputed_with_weights.Rdata")

#obtain weights for estimating the ATT for propensity scores obtained with logistic regression
ELS.data.imputed$weightATTRf <- with(ELS.data.imputed,ifelse(treat==1, 
                                                          1, pScoresRf/(1-pScoresRf))) 

with(ELS.data.imputed, by(weightATTRf,treat,summary))

#obtain weights for estimating the ATE
ELS.data.imputed$weightATERf <- with(ELS.data.imputed,ifelse(treat==1, 
                                                          1/pScoresRf, 1/(1-pScoresRf)))

with(ELS.data.imputed, by(weightATERf,treat,summary))

#save data
save(ELS.data.imputed, file="Chapter3_ELS_data_imputed_with_weights.Rdata", compress=T)

#======================================================

#obtain weights with propensity scores estimated with GBM


#obtain weights for estimating the ATT for propesnity scores obtained with logistic regression
ELS.data.imputed$weightATTGBM <- with(ELS.data.imputed,ifelse(treat==1, 
                                                            1, pScoresGBM/(1-pScoresGBM))) 

with(ELS.data.imputed, by(weightATTGBM,treat,summary))

#obtain weights for estimating the ATE
ELS.data.imputed$weightATEGBM <- with(ELS.data.imputed,ifelse(treat==1, 
                                                            1/pScoresGBM, 1/(1-pScoresGBM)))

with(ELS.data.imputed, by(weightATEGBM,treat,summary))

#save data
save(ELS.data.imputed, file="Chapter3_ELS_data_imputed_with_weights.Rdata", compress=T)