In order to evaluate the impact of a policy intervention on a group of units over time, it is important to correctly estimate the average treatment effect (ATE) measure. Due to lack of robustness of the existing procedures of estimating ATE from panel data, in this paper, we introduce a robust estimator of the ATE and the subsequent inference procedures using the popular approach of minimum density power divergence inference. Asymptotic properties of the proposed ATE estimator are derived and used to construct robust test statistics for testing parametric hypotheses related to the ATE. Besides asymptotic analyses of efficiency and powers, extensive simulation studies are conducted to study the finite-sample performances of our proposed estimation and testing procedures under both pure and contaminated data. The robustness of the ATE estimator is further investigated theoretically through the influence functions analyses. Finally our proposal is applied to study the long-term economic effects of the 2004 Indian Ocean earthquake and tsunami on the (per-capita) gross domestic products (GDP) of five mostly affected countries, namely Indonesia, Sri Lanka, Thailand, India and Maldives.

翻译：为了评估一段时间内政策干预对一组单位的影响,必须正确估计平均处理效果(ATE)措施。由于从小组数据估算ATE的现有程序缺乏稳健性,我们在本文件中采用了一个强有力的估计ATE程序,以及随后采用流行的最小密度功率差异推断法的推论程序。拟议的ATE测算器的占有权性特性是用来为测试与ATE有关的参数假设建立可靠的测试统计数据的。除了对效率和权力进行零星分析外,还进行了广泛的模拟研究,以研究我们在纯数据和受污染数据下拟议的估计和测试程序的有限性能。通过影响功能分析进一步从理论上调查ATE估算器的稳健性。最后,我们的建议用于研究2004年印度洋地震和海啸对五个受影响最大的国家,即印度尼西亚、斯里兰卡、泰国、印度和马尔代夫的(人均)国内产品(国内总产值)的长期经济影响。