Characterization and classification of external quality assessment schemes (EQA) according to objectives such as evaluation of method and participant bias and standard deviation. External Quality Assessment (EQA) Working Group A on Analytical Goals in Laboratory Medicine.

Within the scope of this paper, the Working Group has attempted to place external quality assessment (EQA) within the whole context of quality management in laboratory medicine. First, the objectives of EQA schemes are defined and current EQA schemes evaluated. In most schemes, the objectives are not defined a priori and do not allow the definition of the origin of unacceptable individual results from participants. There is an ongoing trend for making traditional EQA schemes more interesting for the participants. Analysis of the factors involved in analytical quality allow the definition of the essential analytical tasks of educational EQA schemes. Beside these quality control tasks, educational EQA also includes quality assurance elements. EQA today has not only an important role to play in the assessment of each participant's performance but also in the assessment of the method. Efficiency of the schemes and educational impact can be improved by appropriate scheme designs according to objectives. After this theoretical approach, some practical examples of problem related EQA designs are given.