Note that this study defines the input-oriented overall efficiency as a ratio ranging between 0 and 1, and that it is equal to 1 when all slacks are zero. Moreover, it is units-invariant.
While the of model (1) is a weighted average of term efficiencies over the whole terms, model (4) is the model for measuring term efficiency. If the optimal solution for (3) satisfies , then DMUo is considered input-oriented term efficient because the optimal slacks for term t in model (4), are all zero [more specifically, ]: