Normality and other statistical considerations as they relate to selected quantitative measures in the CAP survey.

Investigation of the CAP statistical reports for quantitative tests with respect to the assumption of normality and the method for detecting outliers was performed. Specifically, laboratory measurements of several constituents from the Comprehensive Survey for 1975 were examined. The findings indicate that the assumption of normality, while not exactly valid, is reasonable and not deleterious to the purpose of the Survey, but that the method of determining outliers may be too stringent. A less strict, simpler outlier procedure is suggested as an alternative. It is also observed that other evaluation procedures would be available if more significant digits were reported for the laboratory measurements.