def _jitter(self, durations, event, jitter_level, seed=None):
        """Determine extent to jitter tied event times. Automatically called by fit if tied event times are detected
        """
        np.random.seed(seed)

        if jitter_level <= 0:
            raise ValueError("The jitter level is less than zero, please select a jitter value greater than 0")

        event_times = durations[event != 0].copy()
        n = event_times.shape[0]

        # Determining extent to jitter event times up or down
        shift = np.random.uniform(low=-1, high=1, size=n) * jitter_level
        event_times += shift
        durations_jitter = event_times.align(durations)[0].fillna(durations)

        # Recursive call if event times are still tied after jitter
        if self._check_for_duplicates(durations=durations_jitter, events=event):
            return self._jitter(durations=durations_jitter, event=event, jitter_level=jitter_level, seed=seed)
        return durations_jitter