docs: def _det_inference(self):
          """
          Internal method for determining the inference method
          """
          # 2 random effects with complete design -> gp2KronSum
          # TODO: add check for low-rankness, use GP3KronSumLR and GP2KronSumLR when possible
          if (self.n_randEffs==2) and (~sp.isnan(self.Y).any()):
              rv = 'GP2KronSum'
          else:
              rv = 'GP'
          return rv