[Intralaboratory quality control over random and systematic errors using the combined Shewart-cusum check card]

The method of the within-the-laboratory quality assurance check of the casual and systematic mistakes in the analytical process is presented. The results of the control serums are evaluated by the combined Shewart-cusum check card which is suitable for both casual and systematic mistakes while the classical check card controls the casual mistakes only. The method was used for evaluation of the analytical quality of the results determined by the automatic analyzer "RA 1000 Technicon". The general assessment of the combined method is that the systematic mistakes found are very often of no medical importance but in any case they are an "useful" information for the laboratory specialists in their efforts to provide a reliable laboratory information.