'Predict response variable of a model given exogenous variables.
Parameters
params : array-like
Fitted parameters of the model.
exog : array-like
1d or 2d array of exogenous values.  If not supplied, the
whole exog attribute of the model is used.
linear : bool, optional
If True, returns the linear predictor dot(exog,params).  Else,
returns the value of the cdf at the linear predictor.
Returns
array
Fitted values at exog.'

def predict(self, params, exog=None, linear=False):

    if (exog is None):
        exog = self.exog
    if (not linear):
        return self.cdf(np.dot(exog, params))
    else:
        return np.dot(exog, params)
