Table 4:

Type I error rates for the adjusted difference-in-difference estimator when normality assumption is not satisfied. Errors come from a t-distribution with degrees of freedom described.

Degrees of Freedom	ρ = 0.25	ρ = 0.50	ρ = 0.75
∞ (Normal)	0.05	0.05	0.05
50	0.05	0.05	0.06
10	0.05	0.06	0.08
3	0.05	0.08	0.12