OLS · Diagnostics
Influential Observations
A small number of observations can affect coefficients, fitted values, or conclusions.
Page 1 of 7 · Big Picture
The big picture: Influential Observations
Does one observation have disproportionate influence?
Why a policy analyst should care
An observation can be valid yet dominate a fitted relationship; influence diagnostics identify conclusions that depend heavily on a small part of the data.
Follow the idea from the opening question to a practical decision. These are the conceptual moves this module will develop:
1 Question Does one observation have disproportionate influence?
2 Explore Compare the fitted line with and without a point
3 Formalize Leverage and residual contribution
4 Transfer Conduct an influence audit
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