Contributions to composite sampling

The initial use of composite sampling involved the analysis of many negativ e samples with relatively high laboratory cost (Dorfman sampling). We propo se a method of double compositing and compare its efficiency with Dorfman s ampling. The variability of composite measurement samples has environmental interest (hot spots). The precision of these estimates depends on the kurt osis of the distribution; leptokurtic distributions (gamma (2)> 0) have inc reased precision as the number of field samples is increased. The opposite effect is obtained for platykurtic distributions. In the lognormal case, co verage probabilities are reasonable for sigma< 0.5. The Poisson distributio n can be associated with temporal compositing, of particular interest where radioactive measurements are taken. Sample size considerations indicate th at the total sampling effort is directly proportional to the length of time sampled. If there is background radiation then increasing levels of this r adiation require larger sample sizes to detect the same difference in radia tion.