Causal Impact of Marketing Campaigns: PSM, DiD, Synthetic Control, and DML
Scenario
You have observational data from a marketing campaign where some users/regions were exposed to a campaign (treatment) and others were not (control). You also have outcomes measured before and after the campaign for each unit.
Tasks
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Explain how you would use Propensity Score Matching (PSM) to estimate the treatment effect. Specify assumptions, how you would check overlap and balance, and what robustness checks you would run.
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Explain how you would use Difference-in-Differences (DiD) to estimate the treatment effect. State identification assumptions (e.g., parallel trends), how you would implement it in practice, and robustness checks.
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When is a Synthetic Control Method preferable to DiD? Provide the intuition and the key conditions that make it stronger than standard DiD.
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Describe the Double Machine Learning (DML) framework for causal inference, focusing on why it is useful with high-dimensional covariates. Include the role of cross-fitting and orthogonalization, and the required assumptions.