Table 3 Difference-in-Differences estimation results. The treatment effect (effect of the terrorist attack) is given by the Treatment group x After coefficients and can be interpreted as the absolute percentage decrease in ED visits caused by the attack. The predicted reduction hence ranges from 7.03% (Model 2) to 8.98% (Model 3). The regressions also control for Easter holiday, month, weekday, age group, holiday and age group x holiday fixed effects. These coefficients are omitted for the sake of readability

From: The effect of a terrorist attack on emergency department inflow: an observation study using difference-in-differences methodology