Table 3:

Type I error rate for the different estimators of the ATT. Data is simulated using 4 pre-treatment observations and a covariate associated with the outcome level. Here, μ₀ =0, μ₁ = 2, ρ = 0.5, and σ² = 1. When varying γ₁, β_x = 1. When varying β₁, γ₁ = 1.

Type I Error Rate: Varying γ1					Type I Error Rate: Varying βx
γ1	Unmatched	SC	NN1	NN2	βx	Unmatched	SC	NN1	NN2
0.00	0.05	0.27	0.06	0.03	0.0	0.05	0.30	0.05	0.04
1.00	0.04	0.37	0.05	0.05	0.5	0.05	0.32	0.05	0.04
2.00	0.06	0.36	0.06	0.05	1.0	0.05	0.38	0.05	0.05
3.00	0.06	0.36	0.05	0.05	1.5	0.05	0.36	0.06	0.05
4.00	0.05	0.39	0.05	0.05	2.0	0.04	0.35	0.04	0.03