def deriv2(self, p):
        """
        Second derivative of the link function g''(p)

        implemented through numerical differentiation
        """
        from statsmodels.tools.numdiff import approx_fprime
        p = np.atleast_1d(p)
        # Note: special function for norm.ppf does not support complex
        return np.diag(approx_fprime(p, self.deriv, centered=True))
def deriv2 ( self , p ) : from statsmodels . tools . numdiff import approx_fprime p = np . atleast_1d ( p ) return np . diag ( approx_fprime ( p , self . deriv , centered = True ) )
Second derivative of the link function g''(p)

        implemented through numerical differentiation