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Mean Performance (mean + performance)
Selected AbstractsMethodology of QT-Interval Measurement in the Modular ECG Analysis System (MEANS)ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2009Jan A. Kors Ph.D. Background: QT prolongation as can be induced by drugs, signals the risk of life-threatening arrhythmias. The methodology of QT measurement in the modular ECG analysis system (MEANS) is described. Methods: In the simultaneously recorded leads of the standard 12-lead electrocardiogram (ECG), the QRS complexes are detected by a spatial velocity function. They are typed as dominant or nondominant, and a representative complex per lead is obtained by averaging over the dominant complexes. QRS onset and T end are determined by a template technique, and QT is measured. MEANS performance was evaluated on the 125 ECGs of the common standards for quantitative electrocardiography (CSE) multilead database, of which the waveform boundaries have been released. Results: MEANS detected correctly all 1445 complexes of the CSE library, with one false-positive detection due to a sudden baseline jump. All dominant complexes were correctly typed. The average of the differences between MEANS and reference was less than 2 ms (=1 sample) for both QRS onset and T end, and 2.1 ms for QT duration. The standard deviation of the differences was 3.8, 8.4, and 10.4 ms, respectively. Conclusions: A standard deviation of 10.4 ms for QT measurement seems large when related to the regulatory requirement that a prolongation as small as 5 ms should be detected. However, QT variabilities as encountered in different individuals will be larger than when measured in one individual during pharmacological intervention. Finally, if the U wave is part of the total repolarization, then T and U form a continuum and the end of T becomes questionable. [source] Faking on Personality Measures: Implications for selection involving multiple predictorsINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 1 2009Patrick D. Converse The potential for faking on noncognitive measures in high stakes testing situations remains a concern for many selection researchers and practitioners. However, the majority of previous research examining the practical effects of faking on noncognitive assessments has focused on these measures in isolation, rather than the more common situation in which they are used in combination with other predictors. The present simulation examined the effects of faking on a conscientiousness measure on criterion-related validity, mean performance of those selected, and selection decision consistency when hiring decisions were based on this measure alone vs in combination with two other predictors across a range of likely selection scenarios. Overall, results indicated that including additional predictors substantially reduced , but did not eliminate , the negative effects of faking. Faking effects varied across outcomes and selection scenarios, with effects ranging from trivial to noteworthy even for multiple-predictor selection. Implications for future research and practice are discussed. [source] Indices of Drought Tolerance in Wheat Genotypes at Early Stages of Plant GrowthJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 1 2004S. S. Dhanda Abstract Thirty diverse genotypes of bread wheat were evaluated for seed vigour index, germination percentage, root length, shoot length, root-to-shoot length ratio, coleoptile length and osmotic membrane stability under laboratory conditions. Considerable variation was observed for all the characters. Discrimination among the genotypes on the basis of mean values was better under normal than under moisture stress conditions, indicating suppression of variability under moisture stress conditions. Comparison of mean performance under normal and osmotic stress conditions indicated that the seed vigour index was the most sensitive trait, followed by shoot length, germination percentage and root length. The root-to-shoot length ratio, however, increased under osmotic stress. The magnitude of genetic components of variance and heritability were, in general, lower under osmotic stress than under normal conditions. All the characters except germination percentage, shoot length and coleoptile length showed considerable genetic variability. Heritability in the broad sense was also moderate to high for all the characters under both environments. Due to high heritability and genetic advance great benefit from selection can be expected for the osmotic membrane stability of leaf segments and root-to-shoot length ratio. Moderate progress can be expected from root length and seed vigour index. Correlation studies indicated that the osmotic membrane stability of the leaf segment was the most important trait, followed by root-to-shoot ratio and root length on the basis of their relationships with other traits. [source] Growth in Precursor and Reading-Related Skills: Do Low-Achieving and IQ-Discrepant Readers Develop Differently?LEARNING DISABILITIES RESEARCH & PRACTICE, Issue 1 2002Kimberly J. O'Malley Poor readers who met low achievement and IQ-discrepancy definitions of reading disability were compared with nonimpaired readers on their development of eight precursor and reading-related skills to evaluate developmental differences prior to students' identification as reading disabled. Results indicated no evidence for differences between the two groups of poor readers in the development of the eight skills, with three exceptions. Students in the IQ-discrepant group demonstrated greater growth in letter sound knowledge, greater mean performance in visual-motor integration at the beginning of first grade, and greater deceleration in rapid naming of letters. When compared to the nonimpaired group, low-achieving readers demonstrated poorer performance and development in all skills, while the IQ-discrepant readers demonstrated poorer performance and development in phonemic awareness, rapid naming of letters and objects, spelling, and word reading. The largely null results for comparisons between the two groups of poor readers challenges the validity of the two-group classification of reading disabilities based on IQ-discrepancy. [source] Design of follow-up experiments for improving model discrimination and parameter estimationNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 8 2004Szu Hui Ng Abstract One goal of experimentation is to identify which design parameters most significantly influence the mean performance of a system. Another goal is to obtain good parameter estimates for a response model that quantifies how the mean performance depends on influential parameters. Most experimental design techniques focus on one goal at a time. This paper proposes a new entropy-based design criterion for follow-up experiments that jointly identifies the important parameters and reduces the variance of parameter estimates. We simplify computations for the normal linear model by identifying an approximation that leads to a closed form solution. The criterion is applied to an example from the experimental design literature, to a known model and to a critical care facility simulation experiment. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004 [source] | ||||||||||