Pre-trend test for parallel trends — morie_did_test_parallel

Regresses the outcome on group-by-time interactions in the pre-period and reports both per-period coefficients and a joint Wald (chi-square) test that they are all zero.

Usage

morie_did_test_parallel_trends(
  data,
  outcome,
  treatment,
  time,
  unit = NULL,
  cluster = NULL,
  pre_periods = NULL
)

Arguments

data: A data frame.
outcome: Outcome column name.
treatment: Binary treatment-group indicator.
time: Time column (integer-valued).
unit: Optional unit identifier (currently unused; reserved).
cluster: Cluster variable for robust SE.
pre_periods: Optional explicit list of pre-treatment times.

Value

A list with coefficients, joint_chi2 (and its alias joint_f_stat), joint_df, joint_p_value, parallel_trends_plausible.

Details

For the Callaway-Sant'Anna pre-test on the group-time ATTs prefer did::conditional_did_pretest.