Exact confidence intervals for proportions estimated by group testing

In plant disease assessment, estimation of the proportion of infected units in a population can be greatly facilitated by group testing. Further gains may be possible by the sequential testing of groups of different sizes. The construction of exact confidence intervals is considered here for problems involving unequal sized groups. The recommended method uses an ordering of outcomes based on their associated maximum likelihood estimates, The mettled is compare? with the technique proposed by Sterne (1954, Biometrika 41, 275-278) in which outcomes are ordered according to their probability. An assessment of the prevalence of viruses in carnation populations is used to illustrate the method.