subset_sample: Subset to analystic sample
In evanjflack/cfo.behavioral: Behavioral Hazard and Patient Decision Making

Subset to analystic sample

subset_sample(
  DT,
  subset_vars,
  progress = F,
  balance_vars = NULL,
  inst = "first_mo"
)

`DT`	a data.table
`subset_vars`	variables to subset
`progress`	logical, if TRUE prints where in subsetting process the function is
`balance_vars`	string character, if non-NULL, then estimates balance
`inst`	chatacter, name of instrument to check balance on

a list with three elements

`DT_subset`	Subsetted data.table
`obs`	data.table with observations at each subsetting step
`dt_bal`	data.table with first stage on balance variables at each subset