Statistics, Department of


First Advisor

Kathryn J. Hanford

Second Advisor

Erin E. Blankenship

Date of this Version



A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfilment of Requirements For the Degree of Doctor of Philosophy, Major: Statistics, Under the Supervision of Professors Kathryn J Hanford and Erin E Blankenship. Lincoln, Nebraska: December, 2018.

Copyright (c) 2018 Dola Pathak


Infectious disease assays can be imperfect. When estimating disease prevalence, these imperfections are accounted for by incorporating assay sensitivity and specificity into point and variance estimates. Unfortunately, these accuracy measures are often treated as fixed constants, rather than acknowledging that they are estimates from an assay validation process. The purpose of this study is to show the detrimental effect of not taking into account this sampling variability when samples are obtained through group testing (aka, pooled testing). We show that confidence interval coverage can dramatically decline as the sample size increases for the main sample of interest. As a remedy for this problem, we propose a new confidence interval which takes into account the extra sampling variability. This new interval is shown to obtain coverage near the nominal level.

Heart Rate Variability (HRV) has been used to study stressed induced reaction in humans, and mammal, in general, using non-linear analysis. Studies have also been done to establish synchrony in humans. Non-linear analysis of HRV using recurrence and cross recurrence plots, recurrence and cross recurrence quantification analysis, have also been done to study the feather pecking behavior in chickens. The main purpose of this study is to see if the human study on the degree of synchrony can be replicated for the avian population. If such synchrony exists in the avian population, then it will establish that the degree of synchrony is a primal instinct. Female leghorn chickens were used in the study as they have similar cardiac structure but are evolutionarily distant from mammals. If the presence of synchrony can be established for cagemate hens, it might lead to significant improvement in poultry well-being.

Advisers: Professors Kathryn J Hanford and Erin E Blankenship