We propose the variable intermediate measures SBM model (VSBM) to evaluate the system efficiency of two-stage processes.
We derive the efficient DEA frontier projection based on the VSBM model.
We address the VSBM model on potential conflicts with respect to the intermediate measures.
The system inefficiency is equivalent to the sum of inefficiencies of the two stages.
We obtain efficiency decomposition of two-stage processes based on dual of the VSBM model.