def inverse_deriv(self, z):
    "\n        Derivative of the inverse of the power transform\n\n        Parameters\n        ----------\n        z : array_like\n            `z` is usually the linear predictor for a GLM or GEE model.\n\n        Returns\n        -------\n        g^(-1)'(z) : ndarray\n            The value of the derivative of the inverse of the power transform\n        function\n        "
    if (self.power == 1):
        return np.ones_like(z)
    else:
        return (np.power(z, ((1 - self.power) / self.power)) / self.power)
Derivative of the inverse of the power transform

Parameters
----------
z : array_like
    `z` is usually the linear predictor for a GLM or GEE model.

Returns
-------
g^(-1)'(z) : ndarray
    The value of the derivative of the inverse of the power transform
function
def inverse_deriv(self, z):
    "\n        Derivative of the inverse of the power transform\n\n        Parameters\n        ----------\n        z : array_like\n            `z` is usually the linear predictor for a GLM or GEE model.\n\n        Returns\n        -------\n        g^(-1)'(z) : ndarray\n            The value of the derivative of the inverse of the power transform\n        function\n        "
    if (self.power == 1):
        return np.ones_like(z)
    else:
        return (np.power(z, ((1 - self.power) / self.power)) / self.power)