Physical Sciences and Mathematics Commons^™

The Probability Of Preponderancy: An Alternative To The Intraclass Correlation, Ian R. Harris, Brent D. Burch

Conference on Applied Statistics in Agriculture

We propose a new parameter for measuring the influence of a random effect in a mixed linear model. This is the probability of preponderance of the random effect under study over the other random effects. In a one-way random effects model, this is simply the probability the group random effect is larger in absolute size than the individual random effect (or error). We discuss the meaning of the parameter and relate it to the more familiar intraclass correlation coefficient. The new parameter has the appealing property that it is applicable for any distribution, whereas the intraclass correlation has its origins …

A Simulation Study Of Exponential Semiv Arlo Gram Estimation, Edward E. Gbur, Bruce A. Craig, Hao Zhang

Conference on Applied Statistics in Agriculture

Incorporating the spatial structure of data from agricultural field experiments into inference procedures has become an important topic in recent years. As part of a larger project to determine whether or not reliable predictions and estimates can be obtained for sample sizes often encountered in traditional field experimentation, this paper focuses on the small sample estimation of the parameters of the exponential semivariogram model. Simulation studies were conducted for both expanding and fixed domains. The results indicate large sample to sample variation in sample and fitted semivariograms, neither of which may be "close" to the true model. Distributions of individual …

Effect Of Genetic Potential And Feed On Growth Of Young Bulls For Future Breeding, Benjamin G. Mullinix, Walter E. Neville, Jerry F. Baker

Conference on Applied Statistics in Agriculture

Over a five-year period (1985-1989), a total of 239 bull calves (Angus=119, Hereford=120) were weaned and placed on summer pasture or fed grain concentrate in a feedlot for purpose of studying growth rate of body weight, hip height, and scrotal circumference over 189 days. Average daily gain [ADG, (final wt - weaning wt) / days in period] has been the standard measure of gwwth. However, this does not address how well a particular bull might have performed. ADG values were ranked at each measurement period (0, 21,49,77, 105, 133,161 and 189 days after weaning), changes in rank were determined for …

Comparing Estimation Procedures For Dose-Response Functions, William J. Price, Bahman Shafii, Ken B. Newman, Shane Early, Joseph P. Mccaffrey, Matthew, J. Morra

Conference on Applied Statistics in Agriculture

The dose-response design is often used in agricultural research when it is necessary to measure a biological response at various levels of an experimental factor. This type of problem is common in chemical and pesticide research, however, it can also occur in other disciplines such as plant, animal, soil, and environmental sciences. While the analysis of dose-response data usually involves fitting a regression curve, the primary objective often centers on the estimation of dose related percentiles such as the LD50 or LC50. These measures are useful for comparing the relative efficacy of various treatments, however, the estimation of the specified …

Quadratic Model To Estimate The Doses Causing The Highest Cholesterol Concentration And The Same Cholesterol Concentration As Control Group, Wuyan Zhang, Steve Nissen, Donald Beitz, Philip Dixon

Conference on Applied Statistics in Agriculture

High plasma cholesterol (particularly high LDL-cholesterol) is a high risk factor for coronary heart disease (CHD), which causes a high CHD morbidity and mortality. Besides clinical drugs, more and more interest is focused on finding natural components in the diet that may have hypocholesterolemic effects. Plant sterols are natural components in human diets and found to have cholesterol-lowering effects in humans. Sheanut oil has a relatively high amolmt of plant sterols. Therefore, the two experiments were designed to investigate the hypocholesterolemic effect of sheanut oil in hamsters. The response was not monotonic. Low doses increased plasma cholesterol, but high doses …

Interval Mapping For Autopolyploids, Dachuang Cao, Bruce A. Craig, R. W. Doerge

Conference on Applied Statistics in Agriculture

While extensive progress has been made in quantitative trait locus (QTL) mapping of diploid species, the progress of QTL mapping in polyploids has been limited due to the polyploid's complex genetic architecture. To date, QTL mapping in polyploids has focused primarily on tetraploids with dominant markers and/or codominant markers. In this paper, we extend the interval mapping methodology to any autopolyploid of even ploidy level. Our approach selects a set of likely parental chromosomal configurations (models) using a Bayesian model reduction step. The EM algorithm is then employed to estimate each model's parameters including QTL location, marker dosages, QTL dosages, …

Clustering Environments Based On Crossover Interactions And Using Graphical Approaches To Visualize Clusters, Ken Russell, Kent Eskridge, Daryl Travnicek

Conference on Applied Statistics in Agriculture

Crossover interactions occur in evaluation trails when ranks of cultivars change across environments. Determining groups of environments within which crossover interactions are minimized may facilitate making cultivar recommendations. Model-based approaches to finding such clusters have been previously described. Our goal was to describe a new, non-model based approach of defining these clusters and then apply this method to a 59 environment x eight maize (Zea mays L.) cultivar data set. Hierarchical clustering of a 59 x 59 distance matrix defined two environmental clusters within which the total crossover interaction was reduced by approximately one-third and four clusters within …

New Tools For New Times, Terry C. Nelsen, Debra E. Palmquist

Conference on Applied Statistics in Agriculture

The purpose of this presentation is to challenge statisticians to develop new tools needed by modern scientists. We are in the midst of a Scientific Revolution being driven by computers and the internet. Scientists are gathering huge amounts of data on the usual measurements while continually developing new instruments for new measurements. Data sets full of measurements which may pertain to the scientist's research are easily available on the internet. Scientists are being overwhelmed with data. Agricultural producers and consumers are asking for more information. Scientists need new tools to evaluate variation. They need help with sampling - numbers of …

Small Sample Power Characteristics Of Generalized Mixed Model Procedures For Binary Repeated Measures Data Using Sas, Matthew Beckman, Walter W. Stroup

Conference on Applied Statistics in Agriculture

Researchers in the agricultural and biological sciences often conduct experiments with repeated measures and categorical response variables. Recent advances in statisticalcomputing have made several options available to analyze data from these experiments. For example, SAS has several procedures based on generalized mixed model theory. These include PROC GENMOD, MIXED, NLMIXED, and the GLIMMIX macro. Inference for these procedures depends on asymptotic theory. While statistics literature contains some information about the small-sample behavior, there is much that remains unknown. This presentation will focus on Bernoulli response variables. Power characteristics are compared via simulation for several scenarios involving relatively small repeated measures …

Data Structure With Respect To The Main Effects Model: A Discussion Motivated By A Meta-Analysis Data Set, Dawn M. Vanleeuwen, David S. Birkes, Cynda Clary, Chadelle Robinson

Conference on Applied Statistics in Agriculture

A discussion on data structure relative to the main effects model is motivated by a severely unbalanced meta-analysis data set. This data set is used to highlight the difficulty of assessing data structure when multiple factor data sets are severely unbalanced. Both theoretical results and numerical examples are used to establish that simple approaches to examining data structure using two-way tables provide easily assimilated information about the effect of data unbalance on main effect contrast variances. In addition, notions of balance, proportionality, unbalance, and missing cells with respect to the main effects model are defined in terms of the two-way …

Editor's Preface, Table Of Contents, And List Of Attendees, George A. Milliken

Conference on Applied Statistics in Agriculture

These proceedings contain papers presented in the fifteenth annual annual Kansas State University Conference on Applied Statistics in Agriculture, held in Manhattan, Kansas, April 27-29, 2003.

Alfalfa Disease Management, Paul Vincelli

Kentucky Alfalfa and Stored Forage Conference

Alfalfa can be a vigorous and productive forage crop for Kentucky farmers. Like all farm crops, however, alfalfa is subject to infectious diseases that can limit forage production. Managing these diseases is an important part of economical alfalfa production.

Weed Management In Alfalfa, Jonathan D. Green

Kentucky Alfalfa and Stored Forage Conference

The importance of weed control in forage production should not be overlooked, especially when you consider the high investment associated with alfalfa and other legume forages. Weed management strategies in forage legumes should first focus on cultural practices and then on chemical weed control options. Vigorous, densely growing forage legume stands tend to have fewer weed problems. Thus, cultural and management practices that promote a highly competitive forage stand help prevent many weed problems. These practices include: 1) liming and fertilizing fields based on soil test recommendations; 2) seeding well-adapted, vigorous, and long-lived varieties; 3) buying weed-free seed; 4) cutting …

Alfalfa Haylage And Silage, Michael Collins

Kentucky Alfalfa and Stored Forage Conference

Even with extended grazing systems, typical winter weather conditions in Kentucky necessitate the production of some stored forage for livestock during winter. Hay has traditionally been the way of storing this forage. However, when rain occurs during haymaking operations, the losses can be severe both in yield and in forage quality. Harvest losses are greatest for very dry forage and are low for very wet material like direct cut silage. Silage offers an opportunity to avoid most of the rain damage during harvest because the crop only needs to be left out overnight in most cases to be ready to …

Buying And Selling Alfalfa Hay, Garry D. Lacefield, Jimmy C. Henning

Kentucky Alfalfa and Stored Forage Conference

Alfalfa hay is an important agricultural product. Although often fed on the farms where it is produced, much alfalfa hay is also sold as a cash crop. It often constitutes a major source of income for those who sell it, or a major expense for those who buy it. Such transactions involve billions of dollars nationwide each year.

Forage Testing & Marketing Program, Allen Johnson

Kentucky Alfalfa and Stored Forage Conference

Two thousand and three marks the 141^th year for the Kentucky Department of Agriculture for testing forages. We continue to strive to offer a quality service to producers at the very least cost possible. After all these years we continue to charge only $10.00 per lot or cutting and have expanded our services to try to meet the needs of our forage and livestock producers. In January 2002, we introduced the testing of haylages and have expanded this to cover most of the haylage crops harvested in Kentucky. In cooperation with The University of Kentucky Extension Service, the department …

Producing Quality Alfalfa Hay, Jimmy C. Henning, Garry D. Lacefield

Kentucky Alfalfa and Stored Forage Conference

Hay is one of the most versatile of stored forages in that (1) it can be kept for long periods of time with little loss of nutrients if protected from weather; (2) a large number of crops can be successfully used for hay production; (3) it can be produced and fed in small or large amounts; (4) it can be harvested, stored and fed by hand or the production and feeding can be completely mechanized; and (5) hay can supply most nutrients needed by many classes of livestock. Hay is, therefore, the most commonly used stored feed on most farms.

Alfalfa And Mrls: What We Know After One Year Of Testing, Jimmy C. Henning, Wayne Long

Kentucky Alfalfa and Stored Forage Conference

The onset of mare reproductive loss syndrome in April 2001 in Kentucky lead to much speculation about its cause. Some of these initial 'suspects' included the ergot alkaloids of tall fescue, potential cyanide content of white clover, wide Calcium/Potassium ratios in pasture, fungal mycotoxins and the presence of certain poisonous plants. Certain consultants also indicated that no one should purchase or feed any Kentucky hay in 2001. However, these statements were not based on any hard information, just one person's opinion. But great damage was done to the confidence in Kentucky grown hay.

Alfalfa, The Queen Of Forage Crops — Reflections After Sixty Years Experience With The Crop, Warren C. Thompson

Kentucky Alfalfa and Stored Forage Conference

Yes, it is true I have been involved with alfalfa for 60 years and then some. Fact is I was fortunate enough to pick the World's best forage on which to base much of my career about the same time I fell in love with and married the best lady I ever knew. Betty has stuck with me through these crazy wonderful years. She was largely responsible for matters at home and raising the family. She managed our family and home while I was on the move trying to encourage maybe even coerce farmers in Kentucky and then over the …

Alfalfa For Summer Grazing, Jason Sandefur

Kentucky Alfalfa and Stored Forage Conference

Jason manages the Berle Clay Farm in Paris, Kentucky. The farm has been in the Clay family since the 1770's. The Homestead was built in 1778.

The farming operation consist of approximately 680 acres of orchardgrass-clover, 300 acres of orchardgrass-alfalfa, 210 acres of tall fescue-clover, 100 acres of crops, 13 acres of tobacco and 70 acres in roads, buildings, etc.

Advances In Developing Better Alfalfa Varieties, Jim Moutray

Kentucky Alfalfa and Stored Forage Conference

Alfalfa breeders continue to actively pursue the development of varieties that will bring more benefits to farmers. Yield and better persistence are our highest priorities. Other traits under selection can make alfalfa easier and cheaper to grow, better and safer for livestock and more attractive to livestock.

The goal of this paper is to update you on the types of alfalfa research going on in the U.S., time tables on when you may expect to see these new developments and how they may help you in your operation.

Alfalfa Hay Quality: Terms And Definitions, Garry D. Lacefield

Kentucky Alfalfa and Stored Forage Conference

At the 22^nd Kentucky Alfalfa Conference we discussed the relationship among Alfalfa - Yield-Quality-Persistence. In our presentation, we indicated that all three components must be considered for best management of alfalfa stands. Over the past week, I have looked through the past twenty-two years of Alfalfa Conference Proceedings. It's interesting, but not surprising that we have focused far more attention on yield than on quality and/or persistence.

Alfalfa yield (quantity) and quality are both important; however, it is easier for producers to recognize problems associated with quantity than quality because quantity can be easily assessed visually. Thus, forage quantity …

Foreword [2003], Garry D. Lacefield

Kentucky Alfalfa and Stored Forage Conference

This is the front matter of the proceedings.

Spatial Modeling Of Biomass In Nebraska Windbreaks, Qingjiang Hou, Linda J. Young, James R. Brandle, Michele M. Schoeneberger

Conference on Applied Statistics in Agriculture

Field windbreaks have the potential of sequestering large amounts of carbon. Predicting how much carbon would be sequestered in a newly planted windbreak after ten or more years is of interest. The amount of carbon in a tree depends on its biomass. In a pilot study of Nebraska windbreaks, a Markov random field was used to predict the biomass of green ash in windbreaks as a function of soil and climate conditions. The spatial dependence parameter was significantly different from zero, indicating the presence of small scale variation. In addition to age, the 30 year average summer precipitation and the …

Effect On Boll Weight Of Cotton Plants Planted At Various Densities, B. G. Mullinix, C. W. Bednarz

Conference on Applied Statistics in Agriculture

Previous research has shown that yield of cotton increases with plant density until density reaches 16 to 20 plants m^-2. In 1997 and 1998 cotton was planted at various densities ranging from 2.5 to 22.5 plants m^-2 in a RCB design. Ten row feet (3.048 m) of cotton were cut at ground level in each plot and placed into separate bags. Plant density for each plot was found by counting the number of plants in the bag representing that plot. For each plant, a boll found was placed in a small bag representing the fruiting branch and …

Simulation And Response Surface Methodology To Optimize Winter Wheat Response To Global Climate Change, P. Dhungana, K. M. Eskridge, A. Weiss, P. S. Baenziger

Conference on Applied Statistics in Agriculture

Future climate changes can have a major impact on crop production. But, whatever the climatic changes, crop production can be adapted to climate change by implementing alternative management practices and developing new genotypes that will take full advantage of the future climatic conditions. Since the classical agronomic research approach is not possible in identifying these new agronomic technologies for the future climatic conditions, we used response surface methodology (RSM) in connection with the CERES-Wheat crop model and the HADCM2 climate simulation model to identify optimal configuration of plant traits and management practices that maximize yield of winter wheat under high …

Using Nonlinear Fixed And Mixed Models To Study Acclimation To Heat Stress In Cattle, L. Lan, A. M. Parkhurst, D. A. Spiers, K. M. Eskridge, G. L. Hahn

Conference on Applied Statistics in Agriculture

Researchers studying acclimation of cattle to heat stress want to know if exposure to heat stress in controlled chambers will help cattle adjust to climatic conditions in the field. The four parameter nonlinear PET model is used to study the relationship between core body temperature and ambient temperature. This model works well when cattle are challenged by heat stress but the model is less useful for thermoneutral conditions. Both proc Nlin and Nlmixed are used to compare and contrast the field parameters between the controlled and the potentially acclimated group. Simulation studies were used to compare the effectiveness of proc …

Spline Models For Estimating Heat Stress Thresholds In Cattle, A. M. Parkhurst, D. A. Spiers, G. L. Hahn

Conference on Applied Statistics in Agriculture

Studies of the relationship between animal body temperature and air temperature suggest body temperature is essentially unresponsive until a threshold is reached, then it responds dramatically to increasing air temperature. The goal is to estimate the threshold between the thermoneutral plateau and the beginning of the heat stress challenge. One approach is to fit a polynomial to estimate the knot position and use spline functions to perform linear least squares piecewise polynomial fitting. Another alternative is to use nonlinear regression to estimate the knot or an inflection point of a nonlinear function. In both approaches the cyclic nature of body …

Using Landscape Characteristics As Prior Information For Bayesian Classification Of Remotely Sensed Imagery, William J. Price, Bahman Shafii

Conference on Applied Statistics in Agriculture

Yellow starthistle is a dominant weed of north-central Idaho canyon grasslands. The distribution of yellow starthistle can be affected by general landscape characteristics, such as land use, as well as specific terrain related features such as elevation, slope, and aspect. Slope and aspect can be considered as indicators of plant community composition and distribution. Hence, these variables may be incorporated into prediction models to estimate the likelihood of yellow starthistle occurrence. An empirically derived nonlinear model based on landscape characteristics was developed to predict the likelihood of yellow starthistle occurrence in north central Idaho (Shafii, et al. 1999). While the …

Estimating The Contribution Of Specific Wheat Varieties To State-Level Production, Bingxin Yu, Richard K. Perrin, David B. Marx

Conference on Applied Statistics in Agriculture

This paper addresses measurement issues involved in estimating the benefits from a university wheat breeding program. The conceptual foundation is to estimate the spatial distribution of farm-level yields for varieties in each year, based on Nebraska winter wheat variety test data from 1972 to 2001, with 9-20 locations per year. We can then estimate the state average yield difference that would occur between the portfolios of varieties that farmers actually grew, and the portfolio of varieties excluding those varieties from the university breeding program. This paper reports estimates of the statewide annual yields of individual varieties using a standard fixed …