statsmodels.genmod.qif.QIF.objective¶ QIF.objective(params)[source]¶ Calculate the gradient of the QIF objective function. Parameters:¶ params : array_like¶The model parameters at which the gradient is evaluated. Returns:¶ grad (array_like) – The gradient vector of the QIF objective function. gn_deriv (array_like) – The gradients of each estimating equation with respect to the parameter.