Quality assurance for multichannel hematology instruments. Four years' experience with patient mean erythrocyte indices.

Experience using the Bull patient moving average control system over a four-year period to control a Coulter multichannel hematology counting system is described. The system allowed the abandonment of commercial control materials at an annual saving of almost $3,000 without any deterioration in the quality of laboratory data generated. Guidelines or instrument trouble shooting are outlined. A catalog of all major control problem episodes that occurred during the four-year period is included.