ave_coeff               Aggregate a specified set of terms and
                        corresponding standard errors from an sdid
                        model object
detrend                 Adjust outcomes for differential trends
detrend_factor          Calculate aggregated variance to provide
                        denominator for trend-adjusting outcomes
hosp                    Hospitalization data
hosp_agg                Aggregated hospitalization data
id_tsi                  Identify time-since-intervention
pick_time_refs          Identify time period referents within each
                        cohort.
prep_data               Prepare a data frame to work with sdid()
                        function
sdid                    Fit a staggered difference-in-differences model
select_period           Retrieve a list of interaction terms from a
                        sdid model representing the pre-intervention
                        period
select_terms            Retrieve a list of interaction terms from a
                        sdid model to be passed on for aggregation
summary.sdid_mdl        Summarize an sdid model
ts_plot                 Generates time-series plots, optionally faceted
                        by groups
