data_observed combines the observed dataframe with specific identification
of the columns corresponding to the exposure, outcome, and confounders. It is
an essential input of the multibias_adjust() function.
String type(s) of bias distorting the effect of the exposure
on the outcome. Can choose from a subset of the following: "uc", "em", "om",
"sel". These correspond to uncontrolled confounding, exposure
misclassification, outcome misclassification, and selection bias,
respectively.
exposure
String name of the column in data corresponding to the
exposure variable.
outcome
String name of the column in data corresponding to the
outcome variable.
confounders
String name(s) of the column(s) in data corresponding
to the confounding variable(s).