Showing papers on "Reliability (statistics) published in 2006"

Reliability Evaluation of Power Systems

Abstract: Introduction. Generating Capacity-Basic Probability Methods. Generating Capacity-Frequency and Duration Method. Interconnected Systems. Operating Reserve. Composite Generation and Transmission Systems. Distribution Systems-Basic Techniques and Radial Networks. Distribution Systems-Parallel and Meshed Networks. Distribution Systems-Extended Techniques. Substations and Switching Stations. Plant and Station Availability. Applications of Monte Carlo Simulation. Evaluation of Reliability Worth. Epilogue. Appendix 1: Definitions. Appendix 2: Analysis of the IEEE Reliability Test System. Appendix 3: Thirdorder Equations for Overlapping Events. Solutions to Problems. Index.

Teamwork as an essential component of high-reliability organizations.

Abstract: Organizations are increasingly becoming dynamic and unstable. This evolution has given rise to greater reliance on teams and increased complexity in terms of team composition, skills required, and degree of risk involved. High-reliability organizations (HROs) are those that exist in such hazardous environments where the consequences of errors are high, but the occurrence of error is extremely low. In this article, we argue that teamwork is an essential component of achieving high reliability particularly in health care organizations. We describe the fundamental characteristics of teams, review strategies in team training, demonstrate the criticality of teamwork in HROs and finally, identify specific challenges the health care community must address to improve teamwork and enhance reliability.

Reliability and validity in research

Abstract: This article examines reliability and validity as ways to demonstrate the rigour and trustworthiness of quantitative and qualitative research. The authors discuss the basic principles of reliability and validity for readers who are new to research.

Reliability-based Structural Design

Abstract: Preliminaries.- Probabilistic Analysis.- Methods of Structural Reliability.- Reliability-based Structural Optimization.- Stochastic Expansion for Probabilistic Analysis.- Probabilistic Analysis Examples via Stochastic Expansion.- Summary.

Adults Don't Always Know Best Preschoolers Use Past Reliability Over Age When Learning New Words

Abstract: Children learn much of what they know—from words to their birth dates to the fact that the earth is round—from what other people tell them. But some people are better informants than others. One way children can estimate the credibility of a speaker is by evaluating how reliable that person has been in the past. Even preschoolers prefer learning new words from an adult who has previously labeled objects correctly rather than one who has labeled objects incorrectly (Koenig, Clement, & Harris, 2004). Children may also make predictions about a speaker on the basis of that person’s membership in a particular group. For example, 4-year-olds expect that an unfamiliar adult, but not necessarily an unfamiliar child, knows the meaning of the word hypochondriac (Taylor, Cartwright, & Bowden, 1991). Which of these two cues to a speaker’s credibility—reliability or age—do 3and 4-year-old children find more compelling?

Stochastic Ageing and Dependence for Reliability

Abstract: This book provides a panoramic view of theory and applications of Ageing and Dependence in the use of mathematical methods in reliability and survival analysis. Ageing and dependence are important characteristics in reliability and survival analysis. They affect decisions with regard to maintenance, repair/replacement, price setting, warranties, medical studies, and other areas. Most of the works containing the topics covered here are theoretical in nature. However, this book offers applications, exercises, and examples. It serves as a reference for professors and researchers involved in reliability and survival analysis.

Measuring service quality in higher education: HEdPERF versus SERVPERF

Abstract: Purpose – This paper aims to test and compare the relative efficacy of three measuring instruments of service quality (namely Higher Education PERFormance (HEdPERF), SERVPERF and the moderating scale of HEdPERF‐SERVPERF) within a higher education setting. The objective was to determine which instrument had the superior measuring capability in terms of unidimensionality, reliability, validity and explained variance.Design/methodology/approach – After a pilot test, data were collected from students in two public universities, one private university and three private colleges in Malaysia between January and March 2004, by the “contact person” route. From a total of 560 questionnaires, 381 were usable: a response rate of 68.0 per cent. This sample of nearly 400,000 students in Malaysian tertiary institutions was in line with the generalized scientific guideline for sample size decisions. Data were subjected to regression analysis.Findings – A modified five‐factor structure of HEdPERF is put forward as the mos...

Preanalytical variability: the dark side of the moon in laboratory testing.

Abstract: Remarkable advances in instrument technology, automation and computer science have greatly simplified many aspects of previously tedious tasks in laboratory diagnostics, creating a greater volume of routine work, and significantly improving the quality of results of laboratory testing. Following the development and successful implementation of high-quality analytical standards, analytical errors are no longer the main factor influencing the reliability and clinical utilization of laboratory diagnostics. Therefore, additional sources of variation in the entire laboratory testing process should become the focus for further and necessary quality improvements. Errors occurring within the extra-analytical phases are still the prevailing source of concern. Accordingly, lack of standardized procedures for sample collection, including patient preparation, specimen acquisition, handling and storage, account for up to 93% of the errors currently encountered within the entire diagnostic process. The profound awareness that complete elimination of laboratory testing errors is unrealistic, especially those relating to extra-analytical phases that are harder to control, highlights the importance of good laboratory practice and compliance with the new accreditation standards, which encompass the adoption of suitable strategies for error prevention, tracking and reduction, including process redesign, the use of extra-analytical specifications and improved communication among caregivers.

A survey of transport protocols for wireless sensor networks

Abstract: In this article we present a survey of transport protocols for wireless sensor networks (WSNs). We first highlight several unique aspects of WSNs, and describe the basic design criteria and challenges of transport protocols, including energy-efficiency, quality of service, reliability, and congestion control. We then provide a summary and comparison of existing transport protocols for WSNs. Finally, we discuss several open research problems.

A measurement scale for product innovation performance

Abstract: Purpose – The purpose of this paper is to report the results of a study aimed at conceptualising and developing valid measurements for two key dimensions of product innovation performance‐efficacy and efficiency – in the context of firm competition.Design/methodology/approach – Data were collected from French biotechnology firms. Using structural equations modeling, the constructs’ measurement models were tested and the scale was validated.Findings – The results of the study indicate that the operational measures developed here satisfy the criteria for unidimensionality, reliability, and validity.Research limitations/implications – This study contributes to innovation management research by providing a set of valid and reliable operational measures. These measures are expected to help researchers in theory testing. Because of the sample features, final results should be considered with caution.Practical implications – The proposed measurement scale for product innovation performance could be implemented a...

Reliability Analysis of DSRC Wireless Communication for Vehicle Safety Applications

Abstract: The 802.11-p based dedicated short range communication (DSRC) is being seriously considered as a promising wireless technology for enhancing transportation safety and highway efficiency. However, to-date, there is very little research done in characterizing the reliability of DSRC communication based on real-world experimental data, and its effect on the reliability of vehicle safety applications. Our experimental set-up includes a fleet of three vehicles equipped with DSRC communication system, GPS receiver and a number of vehicle safety applications based on vehicle-to-vehicle communication. This paper analyzes the link-level behavior of DSRC vehicle-to-vehicle communication in a wide variety of traffic environments based on real-world experimental data. In addition, we also characterize the application level reliability of DSRC for vehicle safety communication (VSC) system. Based on our experiments, we show that the reliability of DSRC vehicle-to-vehicle communication is adequate since packet drops do not occur in bursts most of the time. We also show that the application level reliability of VSC applications based on DSRC communication is quite satisfactory. Finally, we develop an analytical model to relate application level reliability with communication reliability and VSC system parameter, laying out a clear way to improve reliability of VSC applications under harsh traffic environments. To the best of our knowledge, this paper is the first to characterize the application-level reliability of DSRC communication for VSC applications based on real-world experimental data. Our findings develop a deep insight into significant characteristics of DSRC communication for highly mobile vehicle-to-vehicle wireless network, which will contribute to better design and evaluation of communication protocols for VSC applications in the future

Customer perceived value in banking services

Abstract: Purpose – The purpose of this research is to analyse the dimensionality of the concept of perceived value in the banking sector, adapting the GLOVAL scale of measurement of perceived value to the banking services sector.Design/methodology/approach – A total of 200 customers of financial entities were surveyed, and structural equations models were used to verify the reliability and validity of the scale of perceived value.Findings – Perceived value is found to be a multidimensional construct composed of six dimensions: functional value of the establishment, functional value of the personnel; functional value of the service; functional value price; emotional value; and social value. A scale of overall perceived value in financial services was obtained, composed of six dimensions and represented by 22 items that are significant for their measurement.Research limitations/implications – In future studies it would be interesting to include items to measure non‐monetary sacrifices, such as waiting times, queues,...

Daily Record of Severity of Problems (DRSP): reliability and validity.

Abstract: The Daily Record of Severity of Problems (DRSP) form was developed to aid in the diagnosis and evaluation of DSM-IV Premenstrual Dysphoric Disorder (PMDD). The reliability and validity of the procedure was tested in two studies. Study A included 27 subjects who ranged from having few or no premenstrual problems to those who met criteria for PMDD. Study B included 243 subjects, all of whom met criteria for PMDD. Individual items and Summary Scores had high test-retest reliability in both studies. Internal consistency of Summary Scores was also high in both studies. Summary Scores had moderate to high correlations with other measures of severity of illness. In addition, items and Summary Scores have been shown to be sensitive to change and to treatment differences in Study B. The DRSP provides sensitive, reliable, and valid measures of the symptoms and impairment criteria for PMDD.

Validation of new clinical quantitative analysis software applicable in spine orthopaedic studies

Abstract: The objective of this study was to evaluate an X-ray films analysis software, i.e. to estimate the reliability and validity of clinical measurements by means of this software. The authors first performed tests of precision and reproducibility of measures. The precision for dynamic modules was estimated at ±2° for the lumbar analysis and ±3° for the cervical one. Mean reproducibility coefficients calculated for postural modules are about 4° for the angular parameters and 3 mm for the linear ones. We also evaluated clinical applicability of the software through its validity. Reference values calculated on a population of healthy subjects showed agreement with the literature. Then, when analysing postural X-ray films of severe scoliotic patients, we found that inter-observer reproducibility coefficients show a lower reliability of measurements; the main cause seems to be the low visibility of anatomic landmarks due to the quality of X-ray films and to the degree of deformity. This study allowed to better estimate the reliability and the usefulness of this tool, allowing for multicentric studies and exchanges.

Validation of Prozone ®: A new video-based performance analysis system

Abstract: Prozone® is a new computerised video system that allows the tracking of many individuals performing a sporting activity. The aim of this study was to validate the Prozone® measurement system when m...

4 Reliability Coefficients and Generalizability Theory

Abstract: Publisher Summary This chapter discusses reliability coefficients as developed in the framework of the classical test theory (CTT) and describes the way the conception and estimation of reliability has been broadened in generalizability theory (G). It also discusses the foundations of CTT and focuses on the traditional methods of estimating reliability. It reviews generalizability theory, its applications, and recent theoretical contributions. In addition to computational procedures, G theory provides a conceptual framework and notational system for characterizing alternative intended universes of generalization, distinguishing fixed versus random facets, and designing efficient measurement procedures. G theory has also clarified the use and interpretation of coefficients and estimated standard errors from CTT. This is of value because, despite the greater sophistication of G theory and the important applications, CTT remains the dominant tool for estimating reliability. However, reliability is just one consideration in the responsible use and interpretation of tests, and not the most important consideration.

‘Rigour’, ‘Ethical Integrity’ or ‘Artistry’? Reflexively Reviewing Criteria for Evaluating Qualitative Research:

Abstract: Qualitative researchers contest and reject the criteria used by quantitative researchers when evaluating their work: those of reliability, validity and generalisability. Instead, qualitative resear...

Reliability and Optimal Maintenance

Abstract: Introduction Imperfect Maintenance and Dependence Maintenance Policies and Analysis A Quasi-renewal Process and Its Applications Reliability and Optimal Maintenance of Series Systems with Imperfect Repair and Dependence Opportunistic Maintenance of Multi-unit Systems Optimal Preparedness Maintenance of Multi-unit Systems Optimal Opportunistic Maintenance of k-out-of-n Systems Reliability and Optimal Inspection-maintenance Models of Multi-degraded Systems Warranty Cost Models with Dependence and Imperfect Repair Software Reliability, Cost, and Optimization Models Monte Carlo Reliability Simulation of Complex Systems

Reliability, mindfulness, and information systems

Abstract: In a world where information technology is both important and imperfect, organizations and individuals are faced with the ongoing challenge of determining how to use complex, fragile systems in dynamic contexts to achieve reliable outcomes. While reliability is a central concern of information systems practitioners at many levels, there has been limited consideration in information systems scholarship of how firms and individuals create, manage, and use technology to attain reliability. We propose that examining how individuals and organizations use information systems to reliably perform work will increase both the richness and relevance of IS research. Drawing from studies of individual and organizational cognition, we examine the concept of mindfulness as a theoretical foundation for explaining efforts to achieve individual and organizational reliability in the face of complex technologies and surprising environments. We then consider a variety of implications of mindfulness theories of reliability in the form of alternative interpretations of existing knowledge and new directions for inquiry in the areas of IS operations, design, and management.

Accuracy and reliability of the ParvoMedics TrueOne 2400 and MedGraphics VO2000 metabolic systems

Abstract: This study examined the accuracy and reliability of the MedGraphics VO2000 (VO2000) portable metabolic system and the ParvoMedics TrueOne 2400 (TrueOne 2400) metabolic cart against the criterion Douglas bag (DB) method. Ten healthy males (age 20 ± 1.7 years) had their gas exchange variables measured at rest and during cycling at 50, 100, 150, 200, and 250 W. Each stage was 10–12 min. For half of the stage gas exchange was measured with the DB and TrueOne 2400 simultaneously and for the other half of the stage gas exchange was measured with the VO2000. The testing was performed on two separate days and the order in which the equipment was used in each stage was randomized. Reliability between days for V E (CV 7.3–8.8%) was similar among devices, however, for VO2, and VCO2 the VO2000 (CV 14.2–15.8%) was less reliable compared to the DB (CV 5.3–6.0%) and TrueOne 2400 (CV 4.7–5.7%). The TrueOne 2400 was not significantly different from the DB at rest or any work rate for V E, VO2, or VCO2 (P ≥ 0.05). The VO2000 was significantly different from the DB for V E at 50–100 W, VO2 at rest and 100–250 W, and VCO2 at rest and 200–250 W (all, P < 0.05). The TrueOne 2400 provides accurate and reliable results for the measurement of gas exchange variables. The VO2000 portable metabolic system was less reliable for measuring VO2 and VCO2 and generally overestimates VO2 at most cycling work rates. Further research is needed to confirm the results found with the VO2000.

Impact of DG placement on reliability and efficiency with time-varying loads

Abstract: Distributed generators (DGs) sometimes provide the lowest cost solution to handling low-voltage or overload problems. In conjunction with handling such problems, a DG can be placed for optimum efficiency or optimum reliability. Such optimum placements of DGs are investigated. The concept of segments, which has been applied in previous reliability studies, is used in the DG placement. The optimum locations are sought for time-varying load patterns. It is shown that the circuit reliability is a function of the loading level. The difference of DG placement between optimum efficiency and optimum reliability varies under different load conditions. Observations and recommendations concerning DG placement for optimum reliability and efficiency are provided in this paper. Economic considerations are also addressed.

The Nature of Accounting Information Reliability: Inferences from Archival and Experimental Research

Abstract: Reliability is an essential characteristic for accounting information to be useful for decision making. Reliability represents the extent to which the information is unbiased, free from error, and representationally faithful (FASB 1980). Despite the central role of reliability, it is a complex and elusive construct of accounting information. Reliability is difficult to specify precisely in accounting standards and practice, and it is difficult to examine directly with research. The primary goal of this paper is to better understand the nature of accounting information reliability by synthesizing archival and experimental research evidence within the context of a framework for accounting information usefulness. Greater understanding of the empirical literature on accounting information reliability should assist standard setters and regulators in establishing financial reporting standards, preparers and auditors in implementing standards, and financial statement users in evaluating accounting information re...

Measuring Physical Environments of Parks and Playgrounds: EAPRS Instrument Development and Inter-Rater Reliability

Abstract: Background: Reliable and comprehensive measurement of physical activity settings is needed to examine environment-behavior relations. Methods: Surveyed park professionals (n = 34) and users (n = 29) identified park and playground elements (e.g., trail) and qualities (e.g., condition). Responses guided observational instrument development for environmental assessment of public recreation spaces (EAPRS). Item inter-rater reliability was evaluated following observations in 92 parks and playgrounds. Instrument revision and further reliability testing were conducted with observations in 21 parks and 20 playgrounds. Results: EAPRS evaluates trail/path, specific use (e.g., picnic), water-related, amenity (e.g., benches), and play elements, and their qualities. Most EAPRS items had goodexcellent reliability, particularly presence/number items. Reliability improved from the original (n = 1088 items) to revised (n = 646 items) instrument for condition, coverage/shade, and openness/visibility items. Reliability was especially good for play features, but cleanliness items were generally unreliable. Conclusions: The EAPRS instrument provides comprehensive assessment of parks’ and playgrounds’ physical environment, with generally high reliability.