Abstract
Education as many other areas of western societies has introduced the output evaluation as a reaction to financial restraints and to increased responsibility at level of individuals or individual institutions. Inputs and processes have become less important than output, and a search for best output indicators has started.
During past decades the culture of evaluation has been developed and output characteristics have been improved in many educational systems. Thus, the concept of value added has emerged as a logical step in the process of improving the knowledge about how schools differ in adding new knowledge, skills or competencies to student?s learning.
Test-based measuring of output was not able to take into account many characteristics - as different student social backgrounds or levels of previous learning - that are crucial for comparing output at all levels, from primary to tertiary education.