code: def incoordination_score(self, data_frame):
          
          diff = data_frame.td[1:-1].values - data_frame.td[0:-2].values
          inc_s = np.var(diff[np.arange(1, len(diff), 2)], dtype=np.float64) * 1000.0
          duration = math.ceil(data_frame.td[-1])
          return inc_s, duration
docs: This method calculates the variance of the time interval in msec between taps
  
              :param data_frame: the data frame
              :type data_frame: pandas.DataFrame
              :return is: incoordination score
              :rtype is: float