Quality control

Abstract: This paper discusses the impact of network architecture on control performance in a class of distributed control systems called networked control systems (NCSs) and provides design considerations related to control quality of performance as well as network quality of service. The integrated network-control system changes the characteristics of time delays between application devices. This study first identifies several key components of the time delay through an analysis of network protocols and control dynamics. The analysis of network and control parameters is used to determine an acceptable working range of sampling periods in an NCS. A network-control simulator and an experimental networked a machine tool have been developed to help validate and demonstrate the performance analysis results and identify the special performance characteristics in an NCS. These performance characteristics are useful guidelines for choosing the network and control parameters when designing an NCS.

Abstract: This paper presents a general model to assess the impact of data and process quality upon the outputs of multi-user information-decision systems. The data flow/data processing quality control model is designed to address several dimensions of data quality at the collection, input, processing and output stages. Starting from a data flow diagram of the type used in structured analysis, the model yields a representation of possible errors in multiple intermediate and final outputs in terms of input and process error functions. The model generates expressions for the possible magnitudes of errors in selected outputs. This is accomplished using a recursive-type algorithm which traces systematically the propagation and alteration of various errors. These error expressions can be used to analyze the impact that alternative quality control procedures would have on the selected outputs. The paper concludes with a discussion of the tractability of the model for various types of information systems as well as an application to a representative scenario.

Abstract: We examine the relation between internal control quality and the accuracy of management guidance. Consistent with managers in firms with ineffective internal controls relying on erroneous internal management reports when forming guidance, we document less accurate guidance among firms reporting ineffective internal controls. This relation extends to a change analysis, and the impact of ineffective internal controls on forecast accuracy is three times larger when the weakness relates to revenues or cost of goods sold — inputs particularly relevant to forecasting earnings. We conclude that internal control quality has an economically significant effect on internal management reports and thus decisions based on these figures.

Abstract: 1 Basic Concepts 2 Companywide Assessment of Quality 3 Quality Improvement and Cost Reduction 4 Operational Quality Planning and Sales Income 5 Quality Control 6 Process Management 7 Strategic Quality Management 8 Organization for Quality 9 Developing a Quality Culture 10 Basic Concepts of Statistics and Probability 11 Statistical Tools for Analyzing Data 12 Understanding Customer Needs 13 Designing for Quality 14 Designing for Quality--Statistical Tools 15 Supply Chain Management 16 Operations--Manufacturing Sector 17 Operations--Service Sector 18 Statistical Process Control 19 Inspection, Test, and Measurement 20 Marketing, Field Performance, and Customer Service 21 Administrative and Support Operations 22 Quality Information Systems 23 Quality Assurance Quality Audit Appendixes