Sargan–Hansen test

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Short description: Statistical test for validity of over-identifying restrictions

The Sargan–Hansen test or Sargan's [math]\displaystyle{ J }[/math] test is a statistical test used for testing over-identifying restrictions in a statistical model. It was proposed by John Denis Sargan in 1958,[1] and several variants were derived by him in 1975.[2] Lars Peter Hansen re-worked through the derivations and showed that it can be extended to general non-linear GMM in a time series context.[3]

The Sargan test is based on the assumption that model parameters are identified via a priori restrictions on the coefficients, and tests the validity of over-identifying restrictions. The test statistic can be computed from residuals from instrumental variables regression by constructing a quadratic form based on the cross-product of the residuals and exogenous variables.[4]:132–33 Under the null hypothesis that the over-identifying restrictions are valid, the statistic is asymptotically distributed as a chi-square variable with [math]\displaystyle{ (m - k) }[/math] degrees of freedom (where [math]\displaystyle{ m }[/math] is the number of instruments and [math]\displaystyle{ k }[/math] is the number of endogenous variables).

See also

References

  1. Sargan, J. D. (1958). "The Estimation of Economic Relationships Using Instrumental Variables". Econometrica 26 (3): 393–415. doi:10.2307/1907619. 
  2. Sargan, J. D. (1988). "Testing for misspecification after estimating using instrumental variables". Contributions to Econometrics. New York: Cambridge University Press. ISBN 0-521-32570-6. 
  3. Hansen, Lars Peter (1982). "Large Sample Properties of Generalized Method of Moments Estimators". Econometrica 50 (4): 1029–1054. doi:10.2307/1912775. 
  4. Sargan, J. D. (1988). Lectures on Advanced Econometric Theory. Oxford: Basil Blackwell. ISBN 0-631-14956-2. 

Further reading