did: Treatment Effects with Multiple Periods and Groups

#' @title County Teen Employment Dataset
#'
#' @description A dataset containing (the log of) teen employment in 500 counties
#'  in the U.S. from 2004 to 2007.  This is a subset of the dataset used in Callaway and
#'  Sant'Anna (2021).  See that paper for additional descriptions.
#'
#' @format A data frame with 2000 rows and 5 variables:
#' \describe{
#'   \item{year}{the year of the observation}
#'   \item{countyreal}{a unique identifier for a particular county}
#'   \item{lpop}{the log of 1000s of population for the county}
#'   \item{lemp}{the log of teen employment in the county}
#'   \item{first.treat}{the year that the state where the county is located
#'    raised its minimum wage, it is set equal to 0 for counties that have
#'    minimum wages equal to the federal minimum wage over the entire
#'    period.}
#'   \item{treat}{whether or not a particular county is treated in that year}
#' }
#' @source Callaway and Sant'Anna (2020)
"mpdta"