Regression · Model comparison
Compare Crude and Adjusted Models on the Same Sample
When adding covariates also removes observations, the model and the population represented by the estimate change at the same time.
Page 1 of 7 · Big Picture
The big picture: Same-Sample Adjustment
Did the coefficient change because of adjustment or because the sample changed?
Why a policy analyst should care
A crude-to-adjusted coefficient change can reflect both a new specification and a new analytic population; fitting both models on the same observations separates those comparisons.
Follow the idea from the opening question to a practical decision. These are the conceptual moves this module will develop:
1 Question What changed: the model or the people?
2 Explore Separate sample change from adjustment
3 Formalize Use three estimates, not two
4 Transfer Audit a changing survey sample
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