c - meta*}}{\rho_{g^{\prime}o}^{group*}}.$$  The TGR with respect to each stage under a concave metafrontier is given by: $$TGR_{g^{\prime}o}^{nc0} = \frac{\rho_{g^{\prime}o}^{nc - meta*0}}{\rho_{g^{\prime}o}^{group*0}};$$ $$TGR_{g^{\prime}o}^{nc0} = \frac{\rho_{g^{\prime}o}^{nc - meta*0}}{\rho_{g^{\prime}o}^{group*0}}