AN INITIAL SYNTHESIS OF AREA 13 229Pu DATA AND OTHER STATISTICAL ANALYSES R. O. Gilbert and L. L. Eberhardt Battelle Memorial Institute Pacific Northwest Laboratory Richland, Washington and D. D. Smith Environmental Monitoring and Support Laboratory U.S. Environmental Protection Agency Las Vegas, Nevada ABSTRACT “ An initial effort is made here to synthesize the Nevada Applied Ecology Group 239°240py data currently available from Area 13 (Project 57) on the Nevada Test Site. Plutonium concentrations for soil, vegetation, small vertebrates, and various tissues in beef cattle (grazed on the Pu-contaminated vegetation) are plotted on a single graph for visual comparison. Hypothetical 2399240py concentrations for lung, skeletal bone, and kidney of a Standard Man assumed to live in and obtain most of his food from the area are also plotted. These hypothetical values were obtained using results from the plutonium transport and dose estimation model of Martin and Bloom (1976). We also discuss here some methods for analyzing and reporting the underlying structure in environmental radionuclide data that are characterized by skewed (asymmetrical) distributions. The inadequacy, in many cases, of reporting only the arithmetic mean and standard error for a data set is emphasized. In particular, we illustrate the construction of a stem-and-leaf display using Pu data from Area 13 for graphically conveying the information content of a data set. A comparison is made between several estimates of central tendency, and the suggestion made that more than one such estimate should be routinely given. Some recent efforts at experimenting with estimating Pu concentration contours with various computer algorithms are also displayed for Area 5 (GMX Site). Contours estimated on log-transformed data appear to have less bias than those obtained on untransformed data. The nearest-neighbor data search routines 237