title: Probits of mixtures.
abstract: The tolerances of individuals (insects, parasites) in a population have a frequency or probability distribution called a tolerance distribution. Many tolerance distributions in bioassay studies can be the result of a rather heterogeneous population of individuals and can often be modelled as a mixture of a number of standard unimodal distributions. A probit analysis can be generalized to the case where the tolerance distribution is a mixture of location and scale parameter distributions. In this article, the existence and determination of the maximum likelihood estimates are investigated. An expectation-maximization (EM) algorithm for probits of mixtures is developed and it is shown that by application of the EM algorithm, the problem of probits of mixtures can be separated into a series of probits of individual component tolerance distributions.
authors: Division of Mathematics and Statistics, CSIRO, Clayton, Victoria, Australia.
authors: T
authors: T
authors: Lwin
authors: P J
authors: PJ
authors: Martin
mesh_terms: D000465:Algorithms; D000818:Animals; D005260:Female; D008954:Models, Biological; D015233:Models, Statistical; D009865:Oocytes / Q000187:drug effects; D010028:Ostertagia / Q000187:drug effects / Q000254:growth & development; D010029:Ostertagiasis / Q000188:drug therapy / Q000662:veterinary*; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy*; D013827:Thiabendazole / Q000627:therapeutic use*; D014252:Trichostrongyloidiasis / Q000662:veterinary*
chemical_list: D013827:Thiabendazole