We study identification and estimation of causal effects of a binary treatment in settings with panel data. We highlight that there are two paths to identification in the presence of unobserved confounders. First, the conventional path based on making assumptions on the relation between the potential outcomes and the unobserved confounders. Second, a design-based path where assumptions are made about the relation between the treatment assignment and the  confounders. We introduce different sets of assumptions that follow the two paths  , and develop double robust approaches to identification where we exploit both approaches, similar in spirit to the double robust approaches to estimation in the program evaluation literature .
We study identification and estimation of causal effects in settings with panel data. Traditionally researchers follow model-based identification strategies relying on assumptions governing the relation between the potential outcomes and the unobserved confounders. We focus on a novel, complementary, approach to identification where assumptions are made about the relation between the treatment assignment and the unobserved confounders. We introduce different sets of assumptions that follow the two paths to identification , and develop a double robust approach. We propose estimation methods that build on these identification strategies .
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of a binary treatment
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We highlight that there are two paths to identification in the presence of unobserved confounders. First, the conventional path based on making assumptions on
Traditionally researchers follow model-based identification strategies relying on assumptions governing
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Second, a design-based path
We focus on a novel, complementary, approach to identification
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unobserved
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to identification
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double robust approaches to identification where we exploit both approaches, similar in spirit to the double robust approaches to estimation in the program evaluation literature
a double robust approach. We propose estimation methods that build on these identification strategies