'Loglikelihood evaluation for each period
Parameters
params : array_like
Array of parameters at which to evaluate the loglikelihood
function.
transformed : boolean, optional
Whether or not `params` is already transformed. Default is True.'

def loglikeobs(self, params, transformed=True):

    params = np.array(params, ndmin=1)
    if (not transformed):
        params = self.transform_params(params)
    results = self._filter(params)
    return np.log(results[5])
