The theory to determine returns to scale (RTS) of decision making units (DMU) with EC2R model is explained.

In this paper,the method is given by providing one common appropriate multiple for some of the outputs(inputs),under the constant inputs(outputs) or respectively appropriate multiples for some of the inputs and outputs to make non effective decision making units effective for DEA (C 2R).

It uses the theory of mathematical programming,effective data and decision making unit to find the mathematical model.

Study of DEA and its application with non-homogeneity decision making units;

The equivalent theorem of DEA efficiency for decision making units under the symmetric models is proposed.

This paper mainly discuss evaluation problems by DEA and adjustment method of decision making units in the sense that the relate effective evaluation index is V0 .

New Methods for Identifying and Ranking Efficient DMU s in DEA;

This paper develops an extension to Data Envelopment Analysis (DEA) allowing for inputs being increasing limitedly,and discusses the efficincy of Decision Making Units (DMUs) in such case,as well as relations between it and its original in efficiency of DMUs.

Each alternative is called a decision making unit(DMU).

A new model for measuring DEA efficiency of decision-making units;

Data envelopment analysis (DEA) is a kind of method appropriate for investigating the relative efficiency of homogeneous decision-making units converting multiple inputs into multiple outputs.

For the reason that conventional data envelopment analysis(DEA) model cannot make further comparison among the efficient ones in evaluating the relative efficiency of decision-making units,this paper proposes the super-efficiency DEA model,which is the extending of the original one and can successfully solve this problem.

Expandation both of decision unit structure and its optimization method in decision network planning;

From the angle of input and output,the ineffective causes of the decision units are analysed through calculation of the decision units not fully using input resources and not sending sufficient outputs and management information aiming at improving the efficiency of the railway network operation are acquired.