Statistics and Technology: Reflections on 35 Years of Change

From the days when statistical calculations were done on mechanical calculators to today, technology has transformed the discipline of statistics. More than just giving statisticians the power to crunch numbers, it has fundamentally changed the way we teach, do research, and consult. In this article, I give some examples of this from my 35 years as an academic statistician

Effect of calf-starter protein solubility on calf performance

Three starters containing differently processed protein supplements were fed to Holstein heifer calves, using an early weaning program. One starter contained soybean meal. The other starters contained soybean grits processed through an extrusion cooker to reduce the protein solubility to an intermediate (PDI> 50%) or low (PDI < 15 %) level. Calf performance was similar on all three starters

A PERMUTATION TEST FOR A REPEATED MEASURES DESIGN

Multivariate permutation tests have advantages over conventional methods in analyzing repeated measures designs. The tests are exact for all sample sizes regardless of the underlying population distribution from which the observations are selected. More importantly the tests do not require a priori assumptions about the form of the correlation structure, obviating the need to check Huynh-Feldt conditions. An example is given of how a multivariate permutation test may be conducted in a context frequently encountered in agricultural research. The SAS program corresponding to this example is also given

USING PRIOR KNOWLEDGE OF THE INTRACLASS CORRELATION TO INCREASE THE POWER OF TESTS FOR TREATMENT MEANS

It is common in agricultural research to have experimental units that consist of multiple observational units. For instance, treatments may be applied to pens of animals, pens being the experimental units, while weights are measured on individual animals, the observational units. If there are a small number of experimental units, the power of statistical tests for treatment effects can be small regardless of the number of observational units. We show that it is possible to increase the power of such statistical tests by taking advantage of prior knowledge of the intraclass correlation. Our assertion is that such prior knowledge is often available although infrequently used. We present several simple methods for taking advantage of this prior knowledge and show that the power of tests based on these methods can be substantially greater than the power of conventional tests specially when the number of experimental units is small

STEP-STRESS TESTING IN AGRICULTIJRE

Step-stress testing has been used for a munber years in engineering. An item is placed on test for a specified period of time. If it does not fail in that time, the stress is increased. This process is repeated for a specified number of stress levels until the item fails. In agriculture, animals or plants may be the test items and dosage of a chemical, amount of fertilizer, temperature, etc, the stress variable. In this paper we suggest several potential applications of step-stress testing in agriculture and present inferential procedures for observations that are distributed exponentially

Farm Level Impacts of a Revenue Based Policy in the 2007 Farm Bill

Revenue-based policy alternatives are thought to be a potential component of the 2007 Farm Bill. This research provides an economic analysis of switching to a revenue assurance farm program for representative farms. Specifically, this research provides a monte-carlo stochastic simulation model that compares the effect of a revenue based safety net policy relative to continuing the 2002 Farm Bill policies for different types of U.S. crop farmers. The results show that both revenue assurance proposals by the National Corn Growers Association leave the majority of farmers, especially feed grain producers, with higher total receipts and higher government payments.Agricultural and Food Policy,

Effect of various dosages of Ralgro® in the suckling period on weight gain during the growing period

We studied how implanting with various dosages of Ralgro® during the suckling period affected gains in the growing period. Preweaning performance was reported in the 1985 Cattlemen\u27s Day Report. All calves, regardless of suckling period treatment, received 36 mg Ralgro® at the start of the growing period. Average daily gains during the growing period were similar for all treatments. Consequently, the added weight obtained from the suckling-period implants was still present at the end of the growing period

THE ALIGNED RANK TRANSFORM PROCEDURE

Recent work has shown that the rank transform methodology is flawed when applied to multifactor designs with interactions. A simple fix-up is proposed and shown to apply to designs typical of those found in agricultural research including split-plots. Simulation results suggest that the fix-up provides a valid procedure for analyzing multifactor designs when error distributions are symmetric or moderately skewed. The procedure appears to have power advantages over normal theory ANOVA when error distributions are heavy tailed

Neutrophil and lymphocyte response to vitamins C and E supplementation in young calves

Calves were bottle-fed milk replacers at 10% of weekly adjusted body weight for 8 wk. Treatments were 1) no supplements (control), 2) .16 oz vitamin C, or 3) .16 oz vitamin C plus 125 IU/lb vitamin E. Lymphocytes and neutrophils isolated from day 14 and day 28 blood samples were assayed for neutrophil-mediated S. aureus phagocytosis and antibody-dependent cellular cytotoxicity, and for mitogen induced lymphocyte proliferation. Eye and nasal discharges of calves supplemented with vitamin C and vitamins C plus E were less than those of control calves for wk 1 to 8. Lymphocyte proliferation with the mitogens showed a trend for higher responses at wk 2 in vitamin C plus E supplemented calves. Neutrophils of calves supplemented with vitamin C showed decreased phagocytosis and lysis functions compared to those of control calves at wk 2 and 4. Neutrophil function of calves supplemented with vitamins C plus E was near or slightly higher than that of controls at wk 2 and 4, suggesting that the addition of vitamin E negated the adverse effects that vitamin C alone had on neutrophil functions.; Dairy Day, 1989, Kansas State University, Manhattan, KS, 1989; The 1989 Annual KSU Dairy Day is known as Dairy Day, 198