code: def effectiv_num_data_points(self, kwargs_lens, kwargs_source, kwargs_lens_light, kwargs_ps):
          
          num_linear = 0
          if self._image_likelihood is True:
              num_linear = self.image_likelihood.num_param_linear(kwargs_lens, kwargs_source, kwargs_lens_light, kwargs_ps)
          num_param, _ = self.param.num_param()
          return self.num_data - num_param - num_linear
docs: returns the effective number of data points considered in the X2 estimation to compute the reduced X2 value