Checking Parallel Trends: Pre-Period Slopes, a Placebo Test & a Trend Chart
This lesson is part of the course
In this lesson
You test the key DiD assumption with the pre-period gap trend, a placebo DiD and a line chart, then estimate the effect month by month.
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Lessons in this course
- Correlation vs Causation: Confounding & Simpson's Paradox Locked
- The Gold Standard: Randomised Experiment & Average Treatment Effect Locked
- Difference-in-Differences: The 2×2 Table and the Regression Locked
- Checking Parallel Trends: Pre-Period Slopes, a Placebo Test & a Trend Chart Locked
- Matching: Nearest-Neighbour Controls with MIN, MATCH & INDEX Locked
- Propensity Scores & Inverse Probability Weighting (IPW) Locked
- Regression Discontinuity: The Jump at the Gold-Status Cutoff Locked
- Instrumental Variables: The Wald Estimator from a Randomised Nudge Locked