Gendex-2001: Getting Started and the BIB Module

10 pages, 1 article*Gendex-2001: Getting Started and the BIB Module* (Federer, Walter T.; Gross, Belinda; Nguyen, Nam-Ky; Nshinyabakobeje, Sophonie) 10 page

Estimates of variance components and heritability for seed yield in two soybean populations from an incomplete vs. complete block design

Block designs are used to control heterogeneity within an experimental area. Subsequently when conducting yield trials with several genotypes, each block of the randomized complete block design can become heterogeneous. This study was conducted to compare a RGB design with an incomplete block (ICB) design imposed ex post facto. Estimates of the variance components and heritability were compared across three statistical models for two soybean populations. Population 1 contained forty-five F4:8:9 soybean lines, and Population 2 contained fifty F4:8:9 soybean lines. Both populations were grown in replicated yield trials at six locations in 1985 and 1986. The ICB design would have been advantageous in twenty-one of forty-two (50%) tests because of the large within block heterogeneity. In 36% of the analyses, the block variance decreased with the incomplete block design, and was equal for the two designs in the remaining 1A%. Additionally, the ICB design resulted, at worst, in an error variance that was not more than 2% greater than the RGB design and, in the best case, was 67% lower than the RCB estimate. Consequently, the error ratios (RCB/ICB) were greater than 100% in 64% of the analyses, less than 100% in 12% of the analyses and equal to 100% in 24% of the analyses. The ICB estimates of heritability were greater than the RCB estimates in 36% of the analyses, equal to the RCB estimates in 40% of the analyses and smaller than the RCB estimates in 24% of the analyses. The ICB design would have resulted in greater precision and accuracy in the estimation of variance components across all three statistical models. Diallel phenotypic correlation coefficients were used to place the six locations into two sets of three locations. One set of three locations would have been adequate for selecting the superior soybean genotypes using either design

Recruiting New Teachers to Urban School Districts: What Incentives Will Work

Explores the effectiveness of financial incentives in attracting qualified teachers to low-performing and hard-to-staff schools. Surveys teachers in training on factors in job choices and considers the size of an effective pay incentive and alternatives

Are users more diverse than designs? Testing and extending a 25 years old claim

Twenty-five years ago, Dennis Egan published a review on the impact of individual differences in human-computer interaction, where he claimed that users are more diverse than designs are [5]. While being cited frequently, this claim has not been tested since then. An efficient research design for separating and comparing variance components is presented, together with a statistical model to test Egan’s claim. The results of a pilot study indicate that Egan’s claim does not universally hold. An extension to the claim is suggested, capturing the trade-offs when prioritizing user tasks. An alternative strategy towards universal design is proposed

Express: a web-based technology to support human and computational experimentation

Experimental cognitive psychology has been greatly assisted by the development of general computer-based experiment presentation packages. Typically, however, such packages provide little support for running participants on different computers. It is left to the experimenter to ensure that group sizes are balanced between conditions and to merge data gathered on different computers once the experiment is complete. Equivalent issues arise in the evaluation of parameterized computational models, where it is frequently necessary to test a model's behavior over a range of parameter values (which amount to between-subjects factors) and where such testing can be speeded up significantly by the use of multiple processors. This article describes Express, a Web-based technology for coordinating "clients" (human participants or computational models) and collating client data. The technology provides an experiment design editor, client coordination facilities (e.g., automated randomized assignment of clients to groups so that group sizes are balanced), general data collation and tabulation facilities, a range of basic statistical functions (which are constrained by the specified experimental design), and facilities to export data to standard statistical packages (such as SPSS). We report case studies demonstrating the utility of Express in both human and computational experiments. Express may be freely downloaded from the Express Web site (http://express.psyc.bbk.ac.uk/)

J. N. Srivastava and experimental design

J. N. Srivastava was a tremendously productive statistical researcher for five decades. He made significant contributions in many areas of statistics, including multivariate analysis and sampling theory. A constant throughout his career was the attention he gave to problems in discrete experimental design, where many of his best known publications are found. This paper focuses on his design work, tracing its progression, recounting his key contributions and ideas, and assessing its continuing impact. A synopsis of his design-related editorial and organizational roles is also included

Use of randomisation in clinical trials : a survey of UK practice

Peer reviewedPublisher PD

Effects of exenatide and liraglutide on heart rate, blood pressure and body weight : systematic review and meta-analysis

Objectives: To synthesise current evidence for the effects of exenatide and liraglutide on heart rate, blood pressure and body weight. Design: Meta-analysis of available data from randomised controlled trials comparing Glucagon-like peptide-1 (GLP-1) analogues with placebo, active antidiabetic drug therapy or lifestyle intervention. Participants: Patients with type 2 diabetes. Outcome measures: Weighted mean differences between trial arms for changes in heart rate, blood pressure and body weight, after a minimum of 12-week follow-up. Results: 32 trials were included. Overall, GLP-1 agonists increased the heart rate by 1.86 beats/min (bpm) (95% CI 0.85 to 2.87) versus placebo and 1.90 bpm (1.30 to 2.50) versus active control. This effect was more evident for liraglutide and exenatide long-acting release than for exenatide twice daily. GLP-1 agonists decreased systolic blood pressure by −1.79 mm Hg (−2.94 to −0.64) and −2.39 mm Hg (−3.35 to −1.42) compared to placebo and active control, respectively. Reduction in diastolic blood pressure failed to reach statistical significance (−0.54 mm Hg (−1.15 to 0.07) vs placebo and −0.50 mm Hg (−1.24 to 0.24) vs active control). Body weight decreased by −3.31 kg (−4.05 to −2.57) compared to active control, but by only −1.22 kg (−1.51 to −0.93) compared to placebo. Conclusions: GLP-1 analogues are associated with a small increase in heart rate and modest reductions in body weight and blood pressure. Mechanisms underlying the rise in heart rate require further investigation