Physical Sciences and Mathematics Commons^™

Analysing Binary Data In A Repeated Measurements Setting Using Sas, Eleanor F. Allan

Conference on Applied Statistics in Agriculture

Whilst the repeated measurements methods appropriate for the analysis of normally distributed data are well established, methods for handling binary and categorical data in a repeated measurements context are not so commonly known or used. The application of population averaged models and subject effects models to repeated binary data are discussed and their implementation with the aid of SAS are illustrated by example. comparisons with other approaches are also considered.

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 ninth annual Kansas State University Conference on Applied Statistics in Agriculture, held in Manhattan, Kansas, April 27-29, 1997.

What Leading Alfalfa Producers Do To Produce Quality Hay, Jimmy C. Henning, Garry D. Lacefield, Buddy Sims

Kentucky Alfalfa and Stored Forage Conference

Alfalfa is the highest quality forage legume crop grown in Kentucky and is the number one cash hay crop. Hay raised by Kentucky farmers has been recognized for its quality at local, state (state fair and Kentucky Alfalfa Conference), and national (American Forage and Grassland Council) hay contests. The testing records of the Kentucky Department of Agriculture also document the high quality alfalfa hay of Kentucky. However, little has been written about the farm practices used to produce high quality alfalfa hay in Kentucky. The current practices of top hay growers may be helpful in defining the options available to …

Grazing Alfalfa In Tennessee: Experiences And Opportunities, Gary Bates

Kentucky Alfalfa and Stored Forage Conference

Animal agriculture in the southeastern U.S. is based on forages. This area has the advantage over all other sections of the nation in forage production. From Kentucky to south Florida, with a little planning forage can be grown almost 12 months a year. Forage programs in Tennessee and Kentucky are based primarily around cool-season grasses such as tall fescue and orchardgrass. These grasses grow over a long portion of the year. In fact, producers have to deal with excess forage production during the spring and fall (Fig. 1). The quality and quantity of forage during these times of the year …

Grazing Alfalfa In Lincoln County, Dan Grigson

Kentucky Alfalfa and Stored Forage Conference

Alfalfa grazing is becoming an important practice for our county's large livestock enterprise. Both dairy and beef producers use alfalfa grazing in various parts of their feeding operations. Lincoln County farmers have a reputation for being good forage producers and have over the years produced good yields and good quality alfalfa. Most producers realize that good forage leads to better profits for their livestock enterprises. That's very important to us as the livestock business generates over $21 million in cash receipts annually.

Alfalfa Seed Production In The Western U.S., Garry D. Lacefield

Kentucky Alfalfa and Stored Forage Conference

Alfalfa is the primary forage for the dairy industry in the United States and provides a majority of the nutrients and energy needs for other classes of livestock including beef cattle, horses and sheep.

In order to maximize forage yield, quality and persistence, one should start with high quality seed. Seed must be free of noxious weeds, have a purity higher than 99.5 percent, a germination of 90 percent or higher and true to the variety stated.

Over 80% of the alfalfa seed was grown in the Great Plains and Rocky Mountain states prior to 1948. This was mostly uncertified, …

Do's And Don'ts Of Alfalfa Round Baled Silage, Michael Collins

Kentucky Alfalfa and Stored Forage Conference

Round baled silage provides an option for outside storage of round bales that protects them from weathering. With shorter field exposure times, silage can dramatically increase forage quality compared with hay. Harvest problems caused by wet weather and/or poor drying conditions during spring and for the freeze-down harvest during autumn could be alleviated by incorporating silage into the harvest system.

Alfalfa Hay: Quality Makes The Difference, Garry D. Lacefield, Jimmy C. Henning

Kentucky Alfalfa and Stored Forage Conference

Alfalfa "Queen of the Forage Crops" is one of the most important forage legumes grown in the U.S. It can be grown over a wide range of soil and climatic conditions, it has the highest yield potential and the highest feeding values of all adapted perennial forage legumes. Alfalfa is a versatile crop which can be used for pasture, hay, silage, green-chop, soil improvements and · human consumption (sprouts, etc.).

A Solution To Some Spring-Seeded Alfalfa Problems, Paul C. Vincelli

Kentucky Alfalfa and Stored Forage Conference

One of the most important assignments I received when I assumed this position in 1990 was to address the question, "What is the cause of seeding failure when alfalfa is spring-seeded into soils that remain wet after seeding?" Six years of laboratory and field work have finally borne fruit. Based on our research, we can confidently present Kentucky alfalfa producers with three conclusions and a recommendation.

Manure On Alfalfa: Why, When, And How Much?, Monroe Rasnake

Kentucky Alfalfa and Stored Forage Conference

Manure is an excellent source of nutrients for growing crops. Its' value has been recognized for thousands of years. Before the development of chemical fertilizers, it served as the primary source of nutrients. It has decreased in importance as a nutrient source in this century and in some cases has become a disposal problem. This has led many farmers to consider using it on legume crops such as alfalfa that don't need to have nitrogen added, but will utilize it and other . nutrients in relatively large amounts. The first question to be considered, then, is why apply manure to …

Controlling Weeds In New Seedings And Established Stands, 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. Weeds may reduce forage yield by competing for water, sunlight and nutrients. For example, yield obtained from the first cutting of alfalfa can be significantly reduced by a heavy infestation of common chickweed. In addition to yield losses, weeds can also lower forage quality, increase the incidence of disease and insect problems, cause premature stand loss, and create harvesting problems. In some cases weeds are unpalatable to livestock or may be poisonous.

What I'Ve Learned From Three Years Of Intensive Experience With No-Till Alfalfa, Jimmy C. Henning, Garry D. Lacefield, Andy Anderson

Kentucky Alfalfa and Stored Forage Conference

Three years ago, a project was begun to better understand the 'hands-on' aspects of no-till establishment of legumes especially alfalfa into fescue sod. Although no-till drills and technology had been around for nearly two decades, farmer feedback on the success of no-till establishment was not uniformly good. The University of Kentucky initiated a program called the 'Establishment Initiative' in partnership with seed companies and Agco-Tye to conduct no-till establishment demonstrations of no-till establishment. These demonstrations focused on getting alfalfa and red clover established into fescue sod which had been suppressed with herbicides. The following are some of the lessons learned.

Foreword [1997], Garry D. Lacefield

Kentucky Alfalfa and Stored Forage Conference

This is the front matter of the proceedings.

Wavelet Nonparametric Regression With Dependent Data, Chengjie Xiong, George A. Milliken

Conference on Applied Statistics in Agriculture

Estimation of the regression function has many applications in agriculture and industry. Usually, the regression function is assumed a known functional form which depends on unknown parameters. Nonparametric regression theory makes no such assumption and often uses some kernel functions to form the so-called Watson Nadaraya type estimators. Such estimators were extensively studied by Watson (1964), Nadaraya (1964, 1989) and Collomb (1981, 1985). When the data are independent, these estimators have nice asymptotic convergence properties. When the data are dependent, Gyorfi et al (1989) gave some large sample properties for the Watson-Nadaraya estimators. In this paper, the recently developed theory …

Validity Of 95% T-Confidence Intervals Under Some Transect Sampling Strategies, Stephen N. Sly, Jeffrey S. Pontius, James J. Higgins

Conference on Applied Statistics in Agriculture

Soil pH data were used to assess the capture rates of 95 % t-confidence intervals based on five different transect sampling strategies. Two different sampling methods were considered, "deterministic" and "two-stage simple random sampling". The data used were pH readings at 15 and 30 centimeter depths from two local agricultural fields in the Manhattan, Kansas area. The data provided three distinct populations with three different distributions - skewed left, symmetric, and bimodal. The total number of transects randomly sampled was 2, 5, and 10. The total number of points sampled along each transect was 2, 7 and 14. The 95% …

Designing Speech Interface Applications For Acquisition Of Agricultural Information, Jeffrey Willers, Susan Bridges, Xiaofeng Ma, James Mckinion, Jean Liang

Conference on Applied Statistics in Agriculture

It will be argued that customary software design strategies, by themselves, fall short when designing speech recognition applications. Concepts of experimental design and analysis are also necessary for developing speech interface software. This study demonstrates that these tools can be advantageous to the software developer, especially if the prototype methodology model of software development is applied. A case study for the problem of developing a speech interface for collecting, or mapping, information on cotton plant growth is presented. The acquisition of cotton plant map data is a 'hands and eyes' busy task that requires considerable investment to record and convert …

A New Approach To Teaching Natural Resource Sampling, Kenneth M. Portier, Loukas G. Arvanitis, Daniel Brackett

Conference on Applied Statistics in Agriculture

A basic undergraduate course in statistics is often not adequate for students in renewable natural resource programs such as wildlife, forestry, fisheries, and related subjects. A strong foundation in the basics of sampling in time and space of forest, vegetation, wildlife and fish populations is needed. A brief account of our experience in teaching such a course over the last three years along with progress on developing course-related material and activities is reported. This includes the development of: 1) computer-based simulations; 2) in-class participation simulations to illustrate the basic concepts of sampling in space and time; 3) exercises to introduce …

Experimentation Science: A Process Approach For The Complete Design Of An Experiment, D. D. Kratzer, K. A. Ash

Conference on Applied Statistics in Agriculture

Experimentation Science is introduced as a process through which the necessary steps of experimental design are all sufficiently addressed. Experimentation Science is defined as a nearly linear process of objective formulation, selection of experimentation unit and decision variable(s), deciding treatment, design and error structure, defining the randomization, statistical analyses and decision procedures, outlining quality control procedures for data collection, and finally analysis, presentation and interpretation of results. The protocol description form (PDF) is introduced as an instrument to guide the implementation and documentation of the Experimentation Science process.

Markov Chain Monte Carlo Methods For Modeling The Spatial Pattern Of Disease Spread In Bell Pepper, Jonathan M. Graham

Conference on Applied Statistics in Agriculture

With exponential family models for dependent data, such as the autologistic model for binary spatial lattice data, maximum likelihood estimates can be obtained using Markov chain sampling methods by simulating an ergodic Markov chain which converges weakly to the equilibrium distribution of the model. This Markov chain Monte Carlo maximum likelihood (MCMCML) procedure provides a competitor to the usual pseudolikelihood estimation method often used for modeling discrete lattice data. Within this MCMCML framework, it is also possible to conduct formal inference using MCMC analogues to the usual likelihood ratio, Wald, and Lagrange multiplier tests, for which the asymptotic distributions are …

Confidence Intervals For The Coefficient Of Variation, Mark E. Payton

Conference on Applied Statistics in Agriculture

The coefficient of variation (CV), defined as the ratio of the standard deviation to the mean, is often used in experimental situations. The exact distribution of the sample CV from a normally distributed population is complicated and obtaining a confidence interval for the population CV in this situation would require using the non-central t distribution and sequential techniques (Koopmans, et al., 1964). This paper explores the use of approximate distributions in determining confidence limits for the CV. The gamma distribution is used to model data appropriate for the calculation of the CV. A Monte Carlo simulation is performed to evaluate …

Estimation Of Kinetic Parameters Associated With Nutrient Uptake By An Intact Plant Root System, Edward Gbur, Craig Beyrouty

Conference on Applied Statistics in Agriculture

Several mechanistic models have been developed for the prediction of nutrient uptake at low concentrations from the soil by a plant root system. Claassen and Barber (1974 Plant Physiology 54, 564-568; 1976 Agronomy Journal 68, 961-964) presented an experimental procedure to obtain data from intact plants to fit an ion depletion curve and used the data in a model which they developed to predict nutrient uptake. Their model assumed that nutrient absorption from the soil solution followed Michaelis-Menten kinetics. In this paper, we develop a stochastic version of the Claassen-Barber model and illustrate its application to the estimation of the …

Analysis Of Unbalanced Mixed Model Data: Traditional Anova Versus Contemporary Methods, Ramon C. Littell

Conference on Applied Statistics in Agriculture

Analysis of unbalanced data and analysis of mixed model data are important topics of statistical discussion. Analysis of unbalanced data with fixed effects gives rise to the different types of sums of squares in analysis of variance. Mixed model riata raises issues of determining appropriate error terms for test statistics and standard errors Clf estimates. The situation is even more difficult when the two topics occur together, resulting in unbalanced mixed model data. These problems have plagued users ofPROC GLM in the SAS System. Now, with PROC MIXED available, some of the problems are resolved while others remain. This paper …

Analysis Of Proportions From Split-Plot And Repeated Measures Experiments, Kenneth J. Koehler

Conference on Applied Statistics in Agriculture

Several methods for analyzing proportions from split-plot and repeated measures experiments are illustrated and compared. One approach simply uses analysis of variance for the usual linear mixed model fit to split-plot and repeated measures experiments. Alternatively, logistic regression analysis is considered and a so-called robust estimate of the covariance matrix is used to adjust for possible correlations among responses. Finally, a quasi-likelihood approach to logistic regression analysis that requires more explicit specification of the covariance structure for the observed proportions is considered. These methods are illustrated with the analyses of data from a repeated measures study of acorn consumption by …

Estimation Of Cardinal Temperatures In Germination Data Analysis, Cindy Roche, Bahman Shafii, Donald C. Thill, William J. Price

Conference on Applied Statistics in Agriculture

Seed germination is a complex biological process which is influenced by various environmental and genetic factors. The effects of temperature on plant development are the basis for models used to predict the timing of germination. Estimation of the cardinal temperatures, including base, optimum, and maximum, is essential because rate of development increases between base and optimum, decreases between optimum and maximum, and ceases above the maximum and below the base temperature. Nonlinear growth curves can be specified to model the time course of germination at various temperatures. Quantiles of such models are regressed on temperature to estimate cardinal quantities. Bootstrap …

Long-Term Tillage Effects On Continuous Corn Yields, T. B. Bailey, J. B. Swan, R L. Higgs, W. H. Paulson

Conference on Applied Statistics in Agriculture

Long-term comparisons of alternative tillage systems are needed to evaluate their effect on corn (Zea mays L.) yield under the variable temperature and rainfall conditions of the Corn Belt. Our objective was to evaluate long-term effects of alternative tillage systems on corn growth and yield on low organic matter silt loam soils. The effect of no-tillage (NT), chisel plow (CP), and moldboard plow (MP) treatments on plant density and grain yield was measured from 1981 through 1990 on Palsgrove and Rozetta silt loam (fine-silty, mixed mesic Typic Hapludalfs) soils. Tillage treatments were randomly allocated to plots in 1981 …

An Introduction To Generalized Linear Mixed Models, Charles E. Mcculloch

Conference on Applied Statistics in Agriculture

The generalized linear mixed model (GLMM) generalizes the standard linear model in three ways: accommodation of non-normally distributed responses, specification of a possibly non-linear link between the mean of the response and the predictors, and allowance for some forms of correlation in the data. As such, GLMMs have broad utility and are of great practical importance. Two special cases of the GLMM are the linear mixed model (LMM) and the generalized linear model (GLM). Despite the utility of such models, their use has been limited due to the lack of reliable, well-tested estimation and testing methods. I first describe and …

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 eighth annual Kansas State University Conference on Applied Statistics in Agriculture, held in Manhattan, Kansas, April 28-30, 1996..

Marketing Options For Quality Kentucky Alfalfa Hay, Tom Keene

Kentucky Alfalfa and Stored Forage Conference

As today's farmer becomes more and more business like, running his farming operation as a commercial business, the production of alfalfa hay should be treated no differently. When the farmer makes the decision to plant alfalfa, he should have already done a great deal of research and given a great deal of thought into the markets he is going to try to target for his product. Any successful commercial business looks into market potential even before production begins, whether they produce toys, cars, appliances, computers, etc. Alfalfa hay production should be no different in regards to seeking out various markets …

What Leading Alfalfa Growers Do To Produce Quality Hay, Jimmy C. Henning, Garry D. Lacefield, Buddy Sims

Kentucky Alfalfa and Stored Forage Conference

Alfalfa is the highest quality forage legume crop grown in Kentucky and is the number one cash hay crop. Hay raised by Kentucky farmers has been recognized for its quality at local, state (state fair and Kentucky Alfalfa Conference), and national (American Forage and Grassland Council) hay contests. The testing records of the Kentucky Department of Agriculture also document the high quality alfalfa hay of Kentucky. However, little has been written about the farm practices used to produce high quality alfalfa hay in Kentucky. The current practices of top hay growers may be helpful in defining the options available to …

Are We Making Progress With Hay Quality In Kentucky?, Buddy Sims

Kentucky Alfalfa and Stored Forage Conference

During the Kentucky State Fair, Garry Lacefield asked if I would be on the XVI Kentucky Alfalfa Conference program. Certainly I never miss an opportunity to talk, especially about testing forages. Then in October we communicated again and it was decided that my topic would be "Are We Making Progress With Hay Quality in Kentucky?" Seems like a simple yes or no question! Well ... l elected to think about this under the middle of December. Of course, during this time, the people of the Commonwealth elected a new Commissioner of Agriculture. Your selection was Billy Ray Smith, who throughout …