When Might It Be the Case That a Difference-In-Differences Estimator

question 28

Multiple Choice

When might it be the case that a difference-in-differences estimator still does not identify a consistent estimate of the causal treatment effect?

• A) If the treatment is non-normally distributed.
• B) If there are non-time varying effects that generate differences between treated and non-treated groups.
• C) If there are time varying effects that generate amongst both treated and non-treated groups symmetrically.
• D) If there are time-varying trends that are different amongst treated and non-treated groups.

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