docs: def _compute_cross_validated_residual_here(self, xi, yi, smooth_here):
          """
          Compute cross validated residual.
  
          This is the absolute residual from Eq. 9. in [1]
          """
          denom = (1.0 - 1.0 / self.window_size -
                   (xi - self._mean_x_in_window) ** 2 /
                   self._variance_in_window)
          if denom == 0.0:
              # can happen  with small data sets
              return 1.0
          return abs((yi - smooth_here) / denom)