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Introduction To Selecting Subsets Of Traits For Quantitative Trait Loci Analysis, Tilman Achberger, James C. Fleet, David E. Salt, R. W. Doerge Apr 2010

Introduction To Selecting Subsets Of Traits For Quantitative Trait Loci Analysis, Tilman Achberger, James C. Fleet, David E. Salt, R. W. Doerge

Conference on Applied Statistics in Agriculture

Quantitative trait loci (QTL) mapping is a popular statistical method that is often used in agricultural applications to identify genomic regions associated with phenotypic traits of interest. In its most common form, a QTL analysis tests one phenotypic trait at a time using a variety of research hypotheses that depend on the application. When multiple traits are available, there are considerable benefits to analyzing subsets of biologically related traits in a multipletrait QTL mapping framework. Determining the most informative subset(s) of traits is the critical challenge that we address in this work. We present our approach, as well as simulations …


After Further Review: An Update On Modeling And Design Strategies For Agricultural Dose-Response Experiments, M. J. Frenzel, W. W. Stroup, E. T. Paparozzi Apr 2010

After Further Review: An Update On Modeling And Design Strategies For Agricultural Dose-Response Experiments, M. J. Frenzel, W. W. Stroup, E. T. Paparozzi

Conference on Applied Statistics in Agriculture

Research investigating dose-response relationships is common in agricultural science. This paper is an expansion on previous work by Guo, et al. (2006) motivated by plant nutrition research in horticulture. Plant response to level of nutrient applied is typically sigmoidal, i.e. no response at very low levels, observable response at mid-levels, point-of-diminishing returns and plateau at high levels. Plant scientists need accurate estimates of these response relationships for many reasons, including determining the lower threshold below which plants show deficiency symptoms and the point of diminishing returns, above which excessive doses are economically and environmentally costly. Guo et al. presented models …


A Non-Parametric Empirical Bayes Approach For Estimating Transcript Abundance In Un-Replicated Next-Generation Sequencing Data, Sanvesh Srivastava, R. W. Doerge Apr 2010

A Non-Parametric Empirical Bayes Approach For Estimating Transcript Abundance In Un-Replicated Next-Generation Sequencing Data, Sanvesh Srivastava, R. W. Doerge

Conference on Applied Statistics in Agriculture

Empirical Bayes approaches have been widely used to analyze data from high throughput sequencing devices. These approaches rely on borrowing information available for all the genes across samples to get better estimates of gene level expression. To date, transcript abundance in data from next generation sequencing (NGS) technologies has been estimated using parametric approaches for analyzing count data, namely – gamma-Poisson model, negative binomial model, and over-dispersed logistic model. One serious limitation of these approaches is they cannot be applied in absence of replication. The high cost of NGS technologies imposes a serious restriction on the number of biological replicates …


Nonlinear Regression Parameters As Outcomes: Simple Vs. Sophisticated Analyses, Reid D. Landes Apr 2010

Nonlinear Regression Parameters As Outcomes: Simple Vs. Sophisticated Analyses, Reid D. Landes

Conference on Applied Statistics in Agriculture

Sometimes a nonlinear regression parameter for an individual is the outcome of interest. But due to variability among individuals, the individuals’ regression parameters cannot be estimated with the same amount of precision. This problem of heterogeneous variance complicates the ultimate goal of estimating population-level regression parameters with two usual methods: (i) the simple arithmetic mean of individually estimated regression parameters and (ii) random coefficients regression (RCR). Weights are proposed for each method to account for the heterogeneity problem. The methods are illustrated with chick weights collected over time. Monte Carlo simulation allows comparison of statistical properties of the four estimators …


Approximate Bayesian Approaches For Reverse Engineering Biological Networks, Andrea Rau, Florence Jaffr´Ezic, Jean-Louis Foulley, R. W. Doerge Apr 2010

Approximate Bayesian Approaches For Reverse Engineering Biological Networks, Andrea Rau, Florence Jaffr´Ezic, Jean-Louis Foulley, R. W. Doerge

Conference on Applied Statistics in Agriculture

Genes are known to interact with one another through proteins by regulating the rate at which gene transcription takes place. As such, identifying these gene-to-gene interactions is essential to improving our knowledge of how complex biological systems work. In recent years, a growing body of work has focused on methods for reverse-engineering these so-called gene regulatory networks from time-course gene expression data. However, reconstruction of these networks is often complicated by the large number of genes potentially involved in a given network and the limited number of time points and biological replicates typically measured. Bayesian methods are particularly well-suited for …


On Testing For Significant Quantitative Trait Loci (Qtl) Effects When Variances Are Unequal, Pradeep Singh, Shesh N. Rai Apr 2010

On Testing For Significant Quantitative Trait Loci (Qtl) Effects When Variances Are Unequal, Pradeep Singh, Shesh N. Rai

Conference on Applied Statistics in Agriculture

The basic theory of QTL (Quantitative Trait Loci) mapping is to score a population for a quantitative trait according to the marker genotype, and then to use statistics to identify differences associated with the markers and the quantitative trait of interest. Permutation based methods have been used to estimate threshold values for quantitative mapping. The permutation test based on the Student t-test for equality of means does not control Type I error rate to its nominal value when variances are unequal. In this study we propose a modification of the Student t-test based on the jackknife estimator of population variance. …


Functional Divergence Of Duplicated Genes In The Soybean Genome, Paul L. Auer, R. W. Doerge Apr 2010

Functional Divergence Of Duplicated Genes In The Soybean Genome, Paul L. Auer, R. W. Doerge

Conference on Applied Statistics in Agriculture

The soybean genome has undergone many different evolutionary changes that are observable with modern technologies. Of particular interest to scientists and plant breeders is the fact that the soybean genome exhibits features of genome duplication from millions of years ago. Genes that were copied during the duplication event have since diverged functionally. Identifying functionally divergent duplicate genes may provide insight into the evolution of soybean. To investigate functional divergence, transcripts from seven different tissue samples of pooled soybean messenger RNA were sequenced using the Solexa next-generation sequencer and analyzed for gene expression. We tested differential expression of duplicated genes within …


Generalized Linear Mixed Model Estimation Using Proc Glimmix: Results From Simulations When The Data And Model Match, And When The Model Is Misspecified, Debbie Boykin, Mary J. Camp, Luann Johnson, Matthew Kramer, David Meek, Debra Palmquist, Bryan Vinyard, Mark West Apr 2010

Generalized Linear Mixed Model Estimation Using Proc Glimmix: Results From Simulations When The Data And Model Match, And When The Model Is Misspecified, Debbie Boykin, Mary J. Camp, Luann Johnson, Matthew Kramer, David Meek, Debra Palmquist, Bryan Vinyard, Mark West

Conference on Applied Statistics in Agriculture

A simulation study was conducted to determine how well SAS® PROC GLIMMIX (SAS Institute, Cary, NC), statistical software to fit generalized linear mixed models (GLMMs), performed for a simple GLMM, using its default settings, as a naïve user would do. Data were generated from a wide variety of distributions with the same sets of linear predictors, and under several conditions. Then, the data sets were analyzed by using the correct model (the generating model and estimating model were the same) and, subsequently, by misspecifying the estimating model, all using default settings. The data generation model was a randomized complete block …


Using Time-Series Intervention Analysis To Model Cow Heart Rate Affected By Programmed Audio And Environmental/Physiological Cues, Dean M. Anderson, Norbert Remenyi, Leigh W. Murray Apr 2010

Using Time-Series Intervention Analysis To Model Cow Heart Rate Affected By Programmed Audio And Environmental/Physiological Cues, Dean M. Anderson, Norbert Remenyi, Leigh W. Murray

Conference on Applied Statistics in Agriculture

This research is the first use of Box-Jenkins time-series models to describe changes in heart rate (HR) of free-ranging crossbred cows (Bos taurus) receiving both programmed audio cues from directional virtual fencing (DVFTM) devices and non-programmed environmental/physiological cues. The DVFTM device is designed to control the animal's location on the landscape. Polar Accurex® devices were used to capture HR every minute between 19 and 24 March 2003, when three mature free-ranging beef cows, previously habituated to the DVFTM device, were confined to a brush-infested area of an arid rangeland paddock. Global positioning system (GPS) electronics were used to record each …


A Generalized Approach And Computer Tool For Quantitative Genetics Study, Jixiang Wu, Johnie N. Jenkins, Jack C. Mccarty Apr 2010

A Generalized Approach And Computer Tool For Quantitative Genetics Study, Jixiang Wu, Johnie N. Jenkins, Jack C. Mccarty

Conference on Applied Statistics in Agriculture

Quantitative genetics is one of the most important components to provide valuable genetic information for improving production and quality of plants and animals. The research history of quantitative genetics study could be traced back more than one hundred years. Since the Analysis of Variance (ANOVA) methods were proposed by Fisher in 1925, several useful genetic models have been proposed and have been widely applied in both plant and animal quantitative genetics studies. Useful examples included various North Carolina (NC) and diallel cross mating designs. However, many genetic models derived from these mating designs are ANOVA method based, so there are …


Modeling Dna Methylation Tiling Array Data, Gayla Olbricht, Bruce A. Craig, R. W. Doerge Apr 2010

Modeling Dna Methylation Tiling Array Data, Gayla Olbricht, Bruce A. Craig, R. W. Doerge

Conference on Applied Statistics in Agriculture

Epigenetics is the study of heritable changes in gene function that occur without a change in DNA sequence. It has quickly emerged as an essential area for understanding inheritance and variation that cannot be explained by the DNA sequence alone. Epigenetic modifications have the potential to regulate gene expression and may play a role in diseases such as cancer. DNA methylation is a type of epigenetic modification that occurs when a methyl chemical group attaches to a cytosine base on the DNA molecule. To better understand this epigenetic mechanism, DNA methylation profiles can be constructed by identifying all locations of …


Characterizing Thermal Hysteresis In Body Temperature For A Heat Stressed Steer, F. Yang, A. M. Parkhurst, D. A. Spiers, J. B. Gaughan, T. L. Mader, G. L. Hahn Apr 2010

Characterizing Thermal Hysteresis In Body Temperature For A Heat Stressed Steer, F. Yang, A. M. Parkhurst, D. A. Spiers, J. B. Gaughan, T. L. Mader, G. L. Hahn

Conference on Applied Statistics in Agriculture

Studies have shown that exposure of animals to a high ambient temperature environment poses serious threats to their health, performance and productivity. Above a certain threshold an animal's body temperature (Tb) appears to be driven by the hot ambient temperature (Ta). For steers challenged by heat stress, the Tb-Ta relationship shows a dramatic increase in Tb per unit change of Ta and the dynamics of the Tb-Ta relationship follow a pattern which depends on whether Ta is increasing or decreasing. A delay becomes noticeable in a steer’s thermo-regulatory response to Ta when Ta is controlled to be sinusoidal in the …


Evaluating Pen-Day Interactions In Body Temperature Bilogistic Mixed Model For Handling Of Feedlot Heifers During Heat Stress, F. Yang, A. M. Parkhurst, T. M. Brown-Brandl, R. A. Eigenberg, J. A. Nienaber Apr 2010

Evaluating Pen-Day Interactions In Body Temperature Bilogistic Mixed Model For Handling Of Feedlot Heifers During Heat Stress, F. Yang, A. M. Parkhurst, T. M. Brown-Brandl, R. A. Eigenberg, J. A. Nienaber

Conference on Applied Statistics in Agriculture

Daily activities consume the energy of heifers, subsequently causing an elevation of body temperature, depending on the ambient conditions. A better understanding of the dynamics of body temperature (Tb) would be helpful when deciding how to process and handle heifers. It would also lead to specific recommendations on moving heifers under different ambient conditions, especially during the summer. In this study, a bilogistic mixed model is used to describe the dynamics of Tb during the moving event. Data was taken from heifers in pens located at different distances from the heifer work station on four separate summer days under hot …


Characterizing Foraging Patterns Among Cattle And Bonded And Non-Bonded Small Ruminants Using Spatial Point Process Techniques, D. M. Anderson, L. W. Murray, P. Sun, E. L. Fredrickson, R. E. Estell, V. B. Nakamatsu Apr 2010

Characterizing Foraging Patterns Among Cattle And Bonded And Non-Bonded Small Ruminants Using Spatial Point Process Techniques, D. M. Anderson, L. W. Murray, P. Sun, E. L. Fredrickson, R. E. Estell, V. B. Nakamatsu

Conference on Applied Statistics in Agriculture

This paper uses the technique of spatial point processes to describe the spatial patterns of freeranging cattle and small ruminants. Two mixed-species livestock groups were monitored while foraging on 410 ha of brush-infested Southern New Mexico rangeland during July and August 1988. The groups consisted of crossbred Bos taurus and Bos indicus beef cattle with white-faced sheep (Ovis aries) and mohair goats (Capra hircus). The bonded group consisted of small ruminants that had their behaviours modified through socialization with cattle to form a ‘flerd’ in which small ruminants consistently remained near cattle. Small ruminants in the non-bonded group had not …


Modeling Fish Length Distribution Using A Mixture Technique, Bahman Shafii, William J. Price, Charlie Holderman, Cathy Gidley, Paul J. Anders Apr 2010

Modeling Fish Length Distribution Using A Mixture Technique, Bahman Shafii, William J. Price, Charlie Holderman, Cathy Gidley, Paul J. Anders

Conference on Applied Statistics in Agriculture

In fisheries science, length and age are important aspects of fish life history. Length is a function of growth, which provides an integrated measure of the environmental and endogenous conditions, e.g. genetics, affecting individuals and populations. Length at age data can be used to assess quality and quantity of habitat, food availability, or the need for and influence of management activities. Statistical mixture techniques may be used as a means to effectively model fish length distribution. A three-component mixture model, based on normal variates, was employed to describe length distribution in mountain whitefish species. The resulting model provided parameter estimates …


Editor's Preface And Table Of Contents, Weixing Song Apr 2010

Editor's Preface And Table Of Contents, Weixing Song

Conference on Applied Statistics in Agriculture

These proceedings contain papers presented in the twenty-second annual Kansas State University Conference on Applied Statistics in Agriculture, held in Manhattan, Kansas, April 25 - April 27, 2010.