A function that calculates lagged outcomes in a panel data setting. If the data.frame that is passed in has nxT rows, the resulting vector will also have nxT elements with one element for each unit set to be NA
Arguments
- df
the data.frame used in the function
- idname
name of column that holds the unit id
- yname
name of column containing the outcome (or other variable) for which to calculate its outcome in the immediate pre-treatment period
- tname
name of column that holds the time period
- nlags
The number of periods to lag. The default is 1, which computes the lag from the previous period.