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= Exogeneity =

In econometrics, '''exogeneity''' is an assumption about data used for statistical inference.

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== Meaning ==

Exogeneity means that all treatment and control variables are independent of the outcome variable and the error term. So an assumption of exogeneity would be violated if...

 * confounding variables were omitted
 * in time series models, a lagged dependent variable can be correlated to the error term
 * if OLS is mistakenly used on a system of equations (i.e. '''simultaneous equation bias''')

In a [[Econometrics/OrdinaryLeastSquares|mulivariate OLS regression]], the assumption of exogeneity can be expressed mathematically as:

{{attachment:exogeneity.svg}}



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CategoryRicottone