在人们的生产活动和社会活动中常常会遇到这样的问题：经过一段时间之后，需要对具有相同类型的部门或单位（称为决策单元）进行评价，其评价的依据是决策单元的“输入”数据和“输出”数据，输入数据是指决策单元在某种活动中需要消耗的某些量，例如投入的资金总额，投入的总劳动力数，占地面积等等；输出数据是决策单元经过一定的输入之后，产生的表明该活动成效的某些信息量，例如不同类型的产品数量，产品的质量，经济效益等等．再具体些说，譬如在评价某城市的高等学校时，输入可以是学校的全年的资金，教职员工的总人数，教学用房的总面积，各类职称的教师人数等等；输出可以是培养博士研究生的人数，硕士研究生的人数，大学生的人数，学生的质量（德，智，体），教师的教学工作量，学校的科研成果（数量与质量)等等．根据输入数据和输出数据来评价决策单元的优劣，即所谓评价部门（或单位）间的相对有效性．-In people s productive activities and social activities often encounter such a problem: After a period of time, need to have the same type of departments or units (referred to as the decision-making unit) to evaluate the basis for his assessment in decision-making unit "input "Data and" output "data, input data refers to the decision-making unit in certain activities that need to consume certain amount of, for example, the total funds invested, the investment of the total workforce number, area, etc.　output data through the decision-making unit After a certain input to produce the show the effectiveness of the activity of certain amount of information, such as different types of product quantity, product quality, economic efficiency and so on. Be more specific, said, for example, in evaluating a city s institutions of higher learning, the input can be the year the school funds, the total number of faculty, teaching a total area of space, all kinds of titles the number of teachers, etc