1step,rule,n_before,n_after,n_removed,rationale21,drop dependent quarters before 1985-04-01,314,162,152,"AR estimated on post-1985 (Great Moderation) sample, fixed a priori; 1947Q2 also lacks a lag"32,drop dependent quarters 2020Q2-2020Q4,162,159,3,"COVID outliers (-28%, +35%) would dominate OLS as y_t or y_{t-1}"4