Detection of positivity violations (empty levels)

Usage

checkR(data, treatment, outcome, vars, id, levels = NULL, quantiles = 0.1)

data: data frame to detect positivity violations
treatment: the main stratum which all covariates should include all levels of (optional)
outcome: the outcome variable which all covariates should include all levels of (optional)
vars: the covariates to examine for positivity violations. State multiple variables as c(var1, var2, var3) without quotes.
id: column indicating unique patient identifier for returning specific NAs
levels: the number of combinations of covariates. level=1 (default) corresponds to a 2x2 table, whereas level=2 corresponds to 2x2 tables stratified on e.g. treatment
quantiles: quantiles for binning of continuous covariates

prints the variables with positivity violations if present. Otherwise none detected. Also returns as either NULL or character for downstream use.