Assessment of Bull's Mean and Exponentially Adjusted Moving Mean (EAMM) Using Selection of Expected Range in the Red Cell Indices / 대한임상병리학회지

ABSTRACT

BACKGROUND: Because moving means can be easily shiftable according to their crude data, we made a selective expected ranges to calculate the moving means. Bull's mean (exponential factor, P=0.50) and Exponentially Adjusted Moving Mean (EAMM, P=0.66) were assessed. we studied to determine appropriately expected range and exponential factor. METHODS: We made the target values from RBC indices being measured with H-2 hematology autoanalyzer from 800 patients and the expected range from red cell indices data of additional 600 patients. Both moving means using this expected ranges were calculated. The % difference of Bull's mean and EAMM was compared and total mean of (deltaBull's mean/deltaBatch mean) and (deltaEAMM/deltaBatch mean) was compared. RESULTS: The target values were MCV 90.6 fL, MCH 29.8 pg. MCHC 32.8 g/dL. The expected ranges were within +/-6% of their target values. Among the 20 batches obtained from expected range, there were no above +/-3% difference of red cell indices in both moving means. The comparison between % difference of Bull's mean and that of EAMM showed no difference. Total mean of (deltaEAMM/deltaBatch mean) was higher than that of (deltaBull's mean/deltaBatch mean). CONCLUSIONS: The % difference results of Bull's mean and EAMM were basically similiar within the expected range but EAMM method was more sensitive than Bull's mean method under the aspect of specimen effects, so EAMM was more detectable than Bull's mean on the quality control of red cell indices.