A function to calculate outcomes for units in the first time period that is available in a panel data setting (this function can also be used to recover covariates, etc. in the first period).
get_Yi1(df, idname, yname, tname, gname)the data.frame used in the function
name of column that holds the unit id
name of column containing the outcome (or other variable) for which to calculate its outcome in the immediate pre-treatment period
name of column that holds the time period
name of column containing the unit's group