A COMPARISON OF MULTIPLE TESTING METHODS: SPINOSAD AS A TREATMENT FOR LICE ON CATTLE

A common problem in statistics is making multiple tests of hypotheses without controlling for the type I error rate. SAS has identified several different methods to adjust p-values for multiple testing. To compare the effect of these methods, an animal health dataset that deals with the treatment of cattle lice was examined. Clinical trials were conducted in Illinois and Wisconsin to evaluate the efficacy of two formulations of a new product Spinosad, two commercially available positive controls, and an untreated negative control. A baseline lice count was recorded prior to the treatment. After treatment, weekly measurements of lice counts were taken for 8 weeks. Counts of 4 lice species were recorded separately. A linear mixed model analysis was conducted for each species of lice after transforming the counts with a natural logarithm transformation. Simple contrasts between treatment groups at each week were performed. Treatment differences were also compared using 5 multiple testing methods: Bonferroni, Sidak, Holm’s step-down Bonferroni, Hochberg\u27s step-up Bonferroni, and false discovery rate. Seventy-one out of 96 simple tests showed significant differences among the treatment groups. The five multiple testing methods confirmed only 48-67 significances out of the 96 tests. Comparatively, Bonferroni and Sidak methods provided similar and the most conservative multiplicity test results, i.e. fewest significant differences. The Holm’s step-down and Hochberg\u27s step-up Bonferroni methods provided similar but less conservative results. Finally, the false discovery rate method provided the least conservative results

Development of a Linognathus Vituli Infestation Model; Population Dynamics and Host Physiologic Changes in Both Normal and Stressed Cattle

200 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2002.Strong dermal response to infestation was measured through cellular infiltration of the skin by eosinophils, mast cells and lymphocytes. Infested and re-infested calves exhibited a marked IDST response. No systemic cell mediated response was detected. Infested animals mounted a humoral response to a soluble L. vituli antigen, but antibody presence was apparently not protective, meaning resistance to infestation is cell-mediated and at the local level.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Development of a Linognathus Vituli Infestation Model; Population Dynamics and Host Physiologic Changes in Both Normal and Stressed Cattle

200 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2002.Strong dermal response to infestation was measured through cellular infiltration of the skin by eosinophils, mast cells and lymphocytes. Infested and re-infested calves exhibited a marked IDST response. No systemic cell mediated response was detected. Infested animals mounted a humoral response to a soluble L. vituli antigen, but antibody presence was apparently not protective, meaning resistance to infestation is cell-mediated and at the local level.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD