Showing papers on "Intra-rater reliability published in 1977"

The measurement of observer agreement for categorical data

Abstract: This paper presents a general statistical methodology for the analysis of multivariate categorical data arising from observer reliability studies. The procedure essentially involves the construction of functions of the observed proportions which are directed at the extent to which the observers agree among themselves and the construction of test statistics for hypotheses involving these functions. Tests for interobserver bias are presented in terms of first-order marginal homogeneity and measures of interobserver agreement are developed as generalized kappa-type statistics. These procedures are illustrated with a clinical diagnosis example from the epidemiological literature.

Computer-aided reliability estimation

Abstract: Computer-aided reliability estimation (CARE) programs are developed to improve the tools available for estimating the reliability of fault-tolerant systems. A description is presented of a program, called CARE II, which was developed after the first program reported by Mathur (1971). Attention is given to the CARE II reliability model, the CARE II coverage model, and CARE II limitations which are to be rectified in CARE III. It is pointed out that the present coverage model in CARE II is extremely versatile. The major limitation is related to the burden placed on the user to determine the basic parameters from which the coverage calculations are made.

Reliability Optimization in Telephone Switching Systems Design

Abstract: In the design of telephone switching systems, the sequence of reliability design functions can be stated as 1) the formation of reliability objectives, 2) the allocation of these objectives, and 3) the modeling to verify the reliability obtained. Optimization techniques can be used in both reliability allocation and reliability modeling. This paper discusses the formation of reliability objectives and the methods of reliability goal allocation. Modeling examples are presented of a component-level reliability vs. cost trade-off and a system-level reliability analysis.

Quality and Reliability

Abstract: The reliability of a product or system is the probability that it will perform a required function in stated conditions of service for a stated period of time. A high level of reliability is possible only if the quality of the component parts conforms to an adequate design specification. Although reliability engineering and quality control are identifiably separate functions it is obvious that they are complementary.

Reliability of Large Systems

Abstract: Modern plants and processes can involve the accumulation of unnatural concentrations of hostile substances in high energy situations. The safe storage of the ingredients and products of these processes, the controlled disposal of waste and the successful harnessing of the reaction energies are all problems which tax our technological resources. There is now sufficient evidence from recent years to demonstrate the potential of fault situations to cause vast economic losses in terms of plant damage and loss of production, to cause loss of life and injury to numbers of operators and in some cases to cause the effects of the catastrophe to extend far beyond the bounds of the factory fence. The need to objectively measure and regulate reliability has now long since been clear and has stimulated the growth of a formalised methodology of reliability assessment which finds expression in quantitative terms. This quantitative component of assessment offers an analogue scale of performance estimation. By this means alternative design strategies can be decisively compared and the reliability spectrum of the component-sections (at any chosen hierarchical level) of a system can be derived. Also the reliability performance of a system may be assessed with respect to some quoted target criterion. Such a target criterion may be derived in reference to plant economics, plant safety or both. Thus a definitive means of gauging the adequacy of the reliability of systems is provided which is increasingly of value as the scales of our technological activities grow. The ability to regulate the reliability of plant to satisfy explicitly derived performance requirements clearly places a valuable and reassuring tool in the hands of the designer. Not only does the tool enable the correct level of reliability to be designed into a system (which is itself cost effective) but also provides a sufficient break-down of performance constituents to enable the most cost effective means of achieving this level to be found.