title: Effect of uncertainty in total parasite infestation on accuracy and precision of estimates of ectoparasiticide efficacy.
abstract: In animal studies of ectoparasiticide efficacy the total number of parasites with which experimental animals are infested is not always equal to the intended number of parasites (usually n=50 per experimental animal in the case of ticks, and n=50 or n=100 in the case of fleas). That is, in the practical implementation of a study protocol, the infestation of experimental animals may be subject to variability so that total infestation is not known precisely. The purpose of the present study is to assess the impact of this variability on the accuracy and precision of efficacy estimates. The results of a thorough simulation study show clearly that uncertainty in total parasite infestation - of the magnitude encountered in well-controlled animal studies - has virtually no effect on the accuracy and precision of estimators of ectoparasiticide efficacy.
authors.affiliation: Department of Mathematical Statistics and Actuarial Science (IB75), University of the Free State, Bloemfontein 9300, South Africa. Electronic address: schallr@ufs.ac.za.
authors.forename: Robert
authors.initials: R
authors.lastname: Schall
authors.affiliation: Department of Mathematical Statistics and Actuarial Science (IB75), University of the Free State, Bloemfontein 9300, South Africa.
authors.forename: Divan A
authors.initials: DA
authors.lastname: Burger
authors.affiliation: ClinVet International (Pty) Ltd, PO Box 11186, Bloemfontein 9321, South Africa.
authors.forename: Theo P
authors.initials: TP
authors.lastname: Erasmus
mesh_terms: D000818:Animals; D000977:Antiparasitic Agents / Q000592:standards* / Q000627:therapeutic use; D003198:Computer Simulation; D004341:Drug Evaluation / Q000592:standards*; D004478:Ectoparasitic Infestations / Q000188:drug therapy / Q000469:parasitology*; D058267:Flea Infestations / Q000188:drug therapy / Q000469:parasitology; D006790:Host-Parasite Interactions; D059208:Parasite Load / Q000592:standards*; D015203:Reproducibility of Results; D013984:Tick Infestations / Q000188:drug therapy / Q000469:parasitology; D035501:Uncertainty
chemical_list: D000977:Antiparasitic Agents
keywords: Abbott's formula; Beta-binomial model; Ectoparasiticides; Efficacy; Total infestation; Variability in total infestation