gt.bpm can be used to test the hypothesis of absence of endogeneity or correlated model equations/errors or non-random sample selection.
Usage
gt.bpm(object)
Arguments
object
A fitted SemiParBIVProbit object as produced by SemiParBIVProbit().
Value
It returns a numeric p-value corresponding to the null hypothesis $\rho$.
Details
The gradient test was first proposed by Terrell (2002) and it is based on classic likelihood theory results. See Marra et al. (submitted) for full details.
References
Marra G., Radice R. and Filippou P. (submitted), Testing the Hypothesis of Exogeneity in Regression Spline Bivariate Probit Models.
Terrell G. (2002), The Gradient Statistic. Computing Science and Statistics, 34, 206-215.