Analysis of manual reticulocyte counting.

A statistical appraisal of manual reticulocyte enumeration was extensively investigated. Statistically, the counting variability among technologists was significantly worse than expected for a counting (Poisson) process. the proportional error associated with each technologist can exceed 39%. The technologist-to-technologist variation is the major source of inaccuracy at all reticulocyte levels and is attributed to the consistent application of individual criteria in reticulocyte identification. Although results may be clinically useful, it is extremely difficult to obtain manual results with sufficient accuracy to serve as a "reference" reticulocyte method.