位置6的问题 Difference-in-differences is only valid when treated and untreated units have identical values for observable pre-treatment features.TrueFalseDon't Know清除选择

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BlackTom AI · Accepted Answer

Question restatement: The prompt asks about whether Difference-in-Differences is valid only when treated and untreated units have identical values for observable pre-treatment features, with options: True, False, Don't Know.
Option 1: True. This is not correct. In DID, the key requirement is that treated and control groups would have followed the same trend in the absence of treatment (the parallel trends assumption), not that their pre-treatment observable features must be identical. Differences in observables can be controlled for if parallel trends hold (or if you condition on those observables), but identical pre-treatment values are not a strict necessity. Hence this statement misrepresents the core assumption and is misleading.
Option 2: False. This is the correct choice. The validity of DID rests on parallel trends in the potential outcomes for treated and control units in the absence of treatment, not on exact equality of pre-treatment observable characteristics. In practice, researchers check pre-treatment trends and may adjust for observables, but identical pre-treatment values are not a required condition for validity. The nuance is that similar pre-treatment trajectories matter more than identical levels, and other design features may be used to address differences.
Option 3: Don't Know. This option reflects uncertainty. While it’s reasonable to be unsure, the standard interpretation is that identical pre-treatment observable values are not a necessary condition for DID validity, so answering Don't Know would not be correct given standard methodology. If a student truly doesn’t know, this option could be a placeholder, but it’s not the best choice here.
In summary, the statement that DID is valid only when treated and untreated units have identical pre-treatment observable values is incorrect because the critical requirement is parallel trends in the absence of treatment, not identical pre-treatment observables. The correct understanding emphasizes the parallel-trends assumption and, when needed, conditioning on observables or using robustness checks to support validity.

位置6的问题 Difference-in-differences is only valid when treated and untreated units have identical values for observable pre-treatment features.TrueFalseDon't Know清除选择

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类似问题

Select all of the statements that are true about Difference-In-Differences research designs:

The estimate produced by the DiD estimator in this example is:

For these two units, the parallel trends assumption is met.

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