The effects of sample size on reticulocyte counting and stool examination. The binomial and poisson distributions in laboratory medicine.
In tests that involve counting or searching for discrete objects, clinical laboratory specimens that are too small produce insensitive and imprecise test results. We found that ten of 57 surveyed New England hospital laboratories examine less than a 50-mg stool sample for parasite eggs; they are, therefore, unlikely to detect infections characterized by low concentrations of eggs in stool. Conversely, all 57 laboratories use the traditional, appropriate sample size of at least 1,000 RBCs for reticulocyte counting. In this report, we discuss theoretical and practical considerations in small sample testing.
D001772:Blood Cell Count; D019411:Clinical Laboratory Techniques; D005243:Feces / Q000469:parasitology*; D006801:Humans; D010270:Parasite Egg Count; D012156:Reticulocytes; D013223:Statistics as Topic