Statistics and Probability Commons^™

Nuclear Genes That Encode Mitochondrial Proteins For Dna And Rna Metabolism Are Clustered In The Arabidopsis Genome, Annakaisa Elo, Anna Lyznik, Delkin O. Gonzalez, Stephen D. Kachman, Sally A. Mackenzie

Department of Statistics: Faculty Publications

The plant mitochondrial genome is complex in structure, owing to a high degree of recombination activity that subdivides the genome and increases genetic variation. The replication activity of various portions of the mitochondrial genome appears to be nonuniform, providing the plant with an ability to modulate its mitochondrial genotype during development. These and other interesting features of the plant mitochondrial genome suggest that adaptive changes have occurred in DNA maintenance and transmission that will provide insight into unique aspects of plant mitochondrial biology and mitochondrial- chloroplast coevolution. A search in the Arabidopsis genome for genes involved in the regulation of …

Conjugated Linoleic Acid Does Not Improve Insulin Tolerance In Mice, Kimberly M Hargrave, Michael J. Azain, Stephen D. Kachman, Jess Miner

Department of Statistics: Faculty Publications

Objective: To determine if the addition or removal of dietary conjugated linoleic acid (CLA) would alter insulin tolerances in mice from two genetic lines.

Research Methods and Procedures: High metabolic rate (MH) and low metabolic rate (ML) mice were assigned to consume 1) a control diet ad libitum, 2) a control diet at a restricted intake, or 3) a diet containing 1% CLA ad libitum. After 9 weeks, an insulin tolerance test was conducted, and a portion of the mice were killed. All remaining mice consumed the control diet ad libitum. Insulin tolerance tests were conducted 11 and 32 days …

Comparing Bayes Model Averaging And Stacking When Model Approximation Error Cannot Be Ignored, Bertrand S. Clarke

Department of Statistics: Faculty Publications

We compare Bayes Model Averaging, BMA, to a non-Bayes form of model averaging called stacking. In stacking, the weights are no longer posterior probabilities of models; they are obtained by a technique based on cross-validation. When the correct data generating model (DGM) is on the list of models under consideration BMA is never worse than stacking and often is demonstrably better, provided that the noise level is of order commensurate with the coefficients and explanatory variables. Here, however, we focus on the case that the correct DGM is not on the model list and may not be well approximated by …

Adipose Depletion And Apoptosis Induced By Trans-10, Cis-12 Conjugated Linoleic Acid In Mice, Kimberly M. Hargrave, Changlong Li, Brett J. Meyer, Stephen D. Kachman, Diane L. Hartzell, Mary Anne Della-Fera, Jess Miner, Clifton A. Baile

Department of Statistics: Faculty Publications

Objective: To compare the effectiveness of a conjugated linoleic acid (CLA) isomer mixture (mCLA) with each main isomer [trans-10,cis-12 CLA (CLA10,12) and cis-9,trans-11 CLA (CLA9,11)] in causing body lipid loss and adipose tissue apoptosis.

Research Methods and Procedures: Mice selected over 16 generations for high (MH) or low (ML) energy expenditure and a control group (MC) were fed diets containing either soy oil or soy oil plus mCLA, CLA10,12, or CLA9,11 for 5 days in one study and 14 days in a second study.

Results: Mice fed mCLA or CLA10,12 had less body lipid (p _ 0.05), smaller retroperitoneal …

Field-Scale Electrical Conductivity Mapping For Delineating Soil Condition, Cinthia K. Johnson, John Doran, Harold R. Duke, Brian J. Wienhold, Kent M. Eskridge, John F. Shanahan

Department of Statistics: Faculty Publications

Traditional sampling methods are inadequate for assessing the interrelated physical, chemical, and biological soil properties responsible for variations in agronomic yield and ecological potentials across a landscape. Recent advances in computers, global positioning systems, and large-scale sensors offer new opportunities for mapping heterogeneous patterns in soil condition. We evaluated field-scale apparent electrical conductivity (ECa) mapping for delineating soil properties correlated with productivity and ecological properties. A contiguous section of farmland (250 ha), managed as eight fields in a no-till winter wheat (Triticum aestivum L.)–corn (Zea mays L.)–millet (Panicum miliaceum L.)–fallow rotation, was EC_a mapped (≈0- to …

Manifest Characterization And Testing For Certain Latent Properties, A. Yuan, Bertrand S. Clarke

Department of Statistics: Faculty Publications

Work due to Junker and more recently due to Junker and Ellis characterized desired latent properties of an educational testing procedure in terms of a collection of other manifest properties. This is important because one can only propose tests for manifest quantities, not latent ones. Here, we complete the conversion of a pair of latent properties to equivalent conditions in terms of four manifest quantities and identify a general method for producing tests for manifest properties.

Soil Quality Assessment After Weed-Control Tillage In A No-Till Wheat–Fallow Cropping System, Timothy A. Kettler, Drew J. Lyon, John W. Doran, W. L. Powers, Walter W. Stroup

Department of Statistics: Faculty Publications

Adoption of reduced-tillage fallow systems in the western USA is limited by winter annual grass weeds such as downy brome (Bromus tectorum L.). Moldboard plowing is an effective means of controlling downy brome in winter wheat (Tritcum aestivum L.)–fallow systems. The purpose of this study was to assess the influence of plowing and secondary tillage operations, for the purpose of weed control, on soil quality attributes of a silt loam soil that had been cropped in a subtill or no-till (NT) winter wheat–fallow system for more than 20 yr. Compared with undisturbed NT, downy brome populations in plowed …

Estimating The Probability Of Severe Convective Storms: A Local Perspective For The Central And Northern Plains, Preston W. Leftwich Jr.

National Oceanographic and Atmospheric Administration: Technical Reports and Related Materials

Summary and Conclusions

A procedure to estimate probabilities of the occurrence of severe convective storms within local areas has been described. Probabilities were based on a simulated climatology and the relative frequency of severe convective events when a selected site was contained within an operational Outlook or Watch. Combined data from five local areas were used to develop a general model for local probabilities within the central and northern Plains region. Attachment of probabilities to specific products placed values within a framework familiar to both forecasters and "end-users." Application of results in an operational scenario demonstrated representative local probabilities and …

Breeding And Genetics 5: Survival Analysis/Threshold Models, Applications In Survival Analysis, Stephen D. Kachman

Department of Statistics: Faculty Publications

Survival or failure time traits such as herd life and days open are both important economically and pose a number of challenges to an analysis based on linear mixed models. The main features of a survival trait are that it is the time until some event occurs, and some of the observations are censored. Survival models and the associated estimation procedures provide a flexible means of modeling survival traits. In this paper I will discuss the application of survival analysis based on the Weibull distribution. The components that make up a survival model will be presented along with their interpretation. …

Posterior Convergence Given The Mean, Bertrand S. Clarke, J. K. Ghosh

Department of Statistics: Faculty Publications

For various applications one wants to know the asymptotic behavior of w(θ | X), the posterior density of a parameter θ given the mean X of the data rather than the full data set. Here we show that w(θ | X) is asymptotically normal in an L¹ sense, and we identify the mean of the limiting normal and its asymptotic variance. The main results are first proved assuming that X₁,...,X_n,... are independent and identical; suitable modifications to obtain results for the nonidentical case are given sepa- rately. Our results may be used to …

Program Review 1993: Self Study Report Department Of Biometry

Department of Statistics: Reports and Administrative Materials

The CSRS review team applauds the statistical expertise of the Biometry Department which began as the statistical Laboratory in 1957 and culminated with the current academic Department of Biometry. This enhancement has been highlighted by a significant increase in the number of faculty and staff, the initiation of a Master of Science program, and the provision of graduate assistant stipends. With the presence of seven faculty, the imminent increase from seven to fifteen graduate students, the establishment of statistical consulting with numerous IANR faculty, and the diverse research and teaching expertise of the faculty, the department is poised to provide …

Selection Of Stable Cultivars Using A Safety-First Rule, Kent M. Eskridge

Department of Statistics: Faculty Publications

The presence of genotype by environment interaction is of major concern to plant breeders, since large interactions can reduce gains from selection and complicate identification of superior cultivars. Numerous statistics have been proposed to characterize stability of cultivars, yet none of these methods explicitly indicate how stability may be combined with mean yield in choosing superior cultivars. It is assumed that the plant breeder prefers a cultivar with a small probability of low yield. Using a decision-theory concept known as safety-first to model such behavior, an index incorporating mean yield and stability is developed for each of four different definitions …

Interaction Of Maternal Grandsire With Region Of United States And Herd For Calving Ease, Birth Weight And 205-Day Weight, K. J. Hanford, P. J. Burfening, D. D. Kress, Stephen D. Kachman

Department of Statistics: Faculty Publications

Field records supplied by the American Simmental Association from 2-yr-old dams were used to study maternal grandsire • region of the U.S. and maternal grandsire • herd within region (herd/region) interactions. Regions were 1) Montana, North Dakota and South Dakota, 2) Kansas and Nebraska, 3) Texas and Oklahoma and 4) Alabama, Florida, Georgia, Louisiana and Mississippi. Analyses were conducted pairwise with respect to region with the following number of animals in each comparison: 1 (3,964) vs 2 (2,239), 1 (3,996) vs 3 (1,660), 1 (3,418) vs 4 (474), 2 (2,033) vs 3 (1,709), 2 (1,666) vs 4 (443) and 3 …

Studies Concerning The Elimination Of Experimental Error In Comparative Crop Tests, T. A. Kiesselbach

Nebraska Agricultural Experiment Station: Historical Research Bulletins

It is apparent that many sources of error have unconsciously entered into comparative crop yield tests. The very important matter of overcoming variation in soil conditions as a source of experimental error has been quite extensively studied and reported by various investigators during the past decade. The means suggested for reducing such error have been (1) repetition of plats and (2) correction of yields according to check plats planted to a uniform variety or treatment at stated intervals. Both methods have proved of value and a combination of both may often be used advantageously. Some danger always exists of error …