摘要:

Statistical process control (SPC) is traditionally applied to processes that vary about a fixed mean, and where successive observations are viewed as statistically independent. Engineering process control (EPC) is usually applied to processes in which successive observations are related over time, and where the mean drifts dynamically. Thus, EPC seeks to minimize variability by transferring it from the output variable to a related process input (controllable) variable, while SPC seeks to reduce variability by detecting and eliminating assignable causes of variation. This paper shows through simulation that when using EPC it is always better to have an SPC system in place that monitors and acts properly on the root cause of the assignable change.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979508

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The randomized response survey model introduced in 1965 by Warner is reviewed and applied to the analysis of contaminated data, that is, response or reported data that is truthful with probability less than one. Two generic mechanisms are distinguished: an active mechanism whereby the contamination is inserted into the process and hence becomes a statistical design parameter, and a passive mechanism whereby contamination of the response is suspected and hence becomes an analysis parameter. The impact of contamination on the operating characteristics of some common statistical inference procedures is developed for binomial models.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979509

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The impact of leverage, influential observations, and multicollinearity in mixture experiments is discussed. By example, it is shown that consideration of these factors is important in the practical selection of a mixture design. Both standard simplex-type mixture designs and computer-generated designs for constrained hyperpolyhedron regions can have very non-uniform distributions of leverage, and consequently, some design points may exert disproportionate influence on the least squares fit. Generally, multicollinearity is not a serious problem in simplex-type designs, provided that when constraints are present the pseudocomponent transformation is used. However, in computer-generated designs, high levels of multicollinearity may be present. How these potential problems can be evaluated and considered in selecting a mixture design is illustrated.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979510

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Control charts are needed in many manufacturing processes for monitoring the rate of occurrences of events such as nonconforming items. This rate can usually be modeled by the interarrival times for a homogeneous Poisson process, which are independent and identically distributed exponential random variables. The monitoring of the exponential mean provides an alternative method for monitoring the rate of occurrences of events. An extensive numerical study indicates that the reference valuekobtained from the sequential probability ratio test is the optimal chart parameterkfor the exponential CUSUM chart. Graphs of chart parameters are given and these graphs can be used to easily obtain the chart parameters of an optimal exponential CUSUM chart. The relative performance of exponential CUSUM and Poisson CUSUM charts for monitoring the rate of occurrences of events is also assessed.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979511

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The purpose of this paper is to develop a model for simultaneously selecting the optimal target means for both a variables and an attribute quality characteristic. The objective is to maximize the expected profit per item. The expected profit per item depends on the revenue, the production cost, and the cost of maintaining the desired quality level. Optimality conditions are derived for the two target mean settings, from which a computational algorithm is constructed. A numerical example is provided to illustrate the application of the model.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979512

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Exponentially distributed observations arise naturally in the context of monitoring the rate of occurrences of events like nonconforming items. Cumulative sum (CUSUM) control charts are known to be very sensitive in detecting small shifts in the mean. A program is presented for computing average run lengths for CUSUM control charts when observations are exponentially distributed.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979513

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979514

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979515

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979516

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979517

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor