AND
Finding Bad Values in Factorial Designs
by George Box, (September 1990).
Sometimes the results from a designed experiment contain "bad or suspect" values. This article discusses a simple way, due to Cuthbert Daniel, of detecting a bad value. It also describes how you might re-estimate its value. More general issues are considered surrounding observations that appear discrepant. Publication(s): Quality Engineering, 1990-91, Vol.3, No.3, pp.405-410.
UW59
Teaching Quality Improvement by Quality Improvement in Teaching
by Ian Hau, (February 1991).
In response to disturbing challenges ahead, leaders at the University of Wisconsin – Madison are committed to transform the institution to a Total Quality University. As a pilot project in the transformation, this paper describes how students and the instructor worked as a team to improve the quality of teaching in a class. Treating students as customers, the team identified 50 areas that affected the quality of teaching. A class survey revealed six areas where most students indicated problems. The instructor then implemented changes which dramatically reduced the defect rate as viewed by the customers in these areas. For example, the defect rate dropped from 78% to 22% for computer instruction, 56% to 8% for blackboard presentation, and 82% to 20% for overhead presentation. The team also developed a system to transfer their knowledge to the next team to ensure never-ending improvement in the future
UW69
Quality Improvement at the Design Stage – A Cyclic Incremental Approach
by Søren Bisgaard, (May 1991).
Quality control based on inspection and segregation is uneconomical and inefficient. To be effective, quality needs to be considered and planned at the product design stage. In this article we put what seems like detailed problem solving, troubleshooting and statistical experimental design work into the larger context of the design and product development process. To do this we have developed a conceptual model for the design process based on the idea of cyclic incremental improvement. Publication(s): Proceedings of the 17^th NSF Design and Manufacturing Systems Grantees Conference, January 1991, University of Texas, Austin.
UW70
Process Optimization – Going Beyond Taguchi Methods
by Søren Bisgaard, (May 1991).
This paper summarizes a speech given at the May 25, 1990 National Thermal Spray Conference in Long Beach, California. It is an expository paper which motivates the use of RSM for Product and Process Improvement and the sequential approach to experimentation with Taguchi methods. Proceedings of the Third National Thermal Spray Conference, Long Beach, California.
UW71
Understanding Exponential Smoothing – A Simple Way to Forecast Sales and Inventory
by George Box, (April 1991).
This article gives a simple account of exponential smoothing and the way it can be used in forecasting. The meaning of an exponentially weighted moving average (EWMA) is given and the role of the smoothing constant in balancing the need to average data against the need for immediacy in the forecast is discussed. A way of estimating the smoothing constant is presented. Publication(s): Quality Engineering, 199~9l, Vol.3, No.4, pp.561-566.

AND
Feedback Control by Manual Adjustment
by George Box, (April 1991).
While we should always make a dedicated endeavor to bring a process into a state of control by fixing causes of variation, there sometimes remains a tendency for the process to wander from the target. In such a case, some method of feedback adjustment may be needed. This article discusses an easily used manual feedback adjustment chart which is equivalent to integral control used by the control engineer. Publication(s): Quality Engineering, 1991-92, Vol.4, No.1, pp.143-151.

AND
Bounded Adjustment Charts
by George Box, (April 1991).
The feedback adjustment charts discussed in the previous article are valuable when the cost of adjustment is essentially zero. However, when process adjustment is associated with a specific cost (for example, of stopping a machine and changing a tool), it is more economical to use a scheme that requires less frequent adjustment. For this purpose, bounded adjustment charts using an exponentially weighted average of past data may be used. A simple interpolation chart is presented for updating the forecast and indicating when and how large an adjustment is needed. A table is given allowing a scheme to be chosen by balancing a longer average interval between adjustments against the resulting increase in the standard deviation about the target value. Publication(s): Quality Engineering, 1991-92, Vol.4, No.2, pp.331-338.
UW73
The Use of Statistics to Improve Manufacturing Systems
by Søren Bisgaard, (October 1991).
This article presents a general overview of statistical methods applied to solving manufacturing problems. We also provide a specific example of a statistically designed experiment used to study factors affecting robot accuracy. The robot experiment illustrates how manufacturing engineers can improve quality and productivity, and reduce costs by applying relatively simple statistical tools on the shop floor. Publication(s): appeared as "Statistical Tools for Manufacturing" in Manufacturing Review, Vol.6, No.3, pp.192-200.
UW74
Quality Improvement – The New Industrial Revolution
by George Box, (October 1991).
Beginning from Bacon’s famous aphorism that "Knowledge Itself is Power", the underlying philosophy of modern quality improvement is seen as the mobilization of presently available sources of knowledge and knowledge gathering. These resources, often untapped include the following: (i) that the whole workforce possesses useful knowledge and creativity; (ii) that every system by its operation produces information on how it can be improved; (iii) that simple procedures can be learned for better monitoring and adjustment of processes; (iv) that elementary principles of experimental design can increase the efficiency many times over of experimentation for process improvement, development, and research. Publication(s): International Statistical Review, Vol.61, No.1, pp.3-19.
UW75
The Early Years of Designed Experiments in Industry:
Case Study References and Some Historical Anecdotes
by Søren Bisgaard, (November 1991).
Case studies are important because they provide illustrations of the industrial use of designed experiments. However, they are usually hard to come by; nevertheless unknown to many, there are quite a few case studies already published in the literature. Most of them are unfortunately scattered in many different technical and scientific journals, and are not readily available unless one knows where to look. In this article we provide a list of approximately 130 references to case study articles published over the past six decades. We also provide a causerie of historical anecdotes from early initiatives in the use of designed experiments in industry. Publication(s): Quality Engineering, 1992, Vol.4, No.4, pp.547-562.
UW76
Teaching Engineers Experimental Design with a Paper Helicopter
by George Box, November 1991).
How a paper "helicopter" made in a minute or so from a 8 1/2" x 11" sheet of paper can be used to teach principles of experimental design including- conditions for validity of experimentation, randomization, blocking, the use of factorial and fractional factorial designs, and the management of experimentation. Publication(s): Quality Engineering, 1992, Vol.4, No.3, pp. 453459.
UW78
What Can You Find Out From Eight Experimental Runs?
by George Box, (February 1992).
Publication(s): Quality Engineering, 1992, Vol.4, No.4, pp.619-627.

AND
What Can You Find Out From Sixteen Experimental Runs?
by George Box, (February 1992).
Publication(s): Quality Engineering, 1992, Vol.5, No. 11, pp.167-178.
Different ways to use n = 8 and n = 16 experimental runs are described to generate two-level factorial and fractional factorial designs for studying up to n - 1 factors. The roles of "aliases" and of design "resolution" are discussed and the rationales for the employment of designs with different degrees of fractionation are presented.
UW81
A New Design for Quality Paradigm
by Mikkel Mørup (April 1992).
Product development and design has a tremendous influence on the final product quality and the cost of quality. This paper presents a critical look at the position of Design for Quality in western industry and academia. It is suggested that Design for Quality should be enhanced in the context of design methodology in order to better fit the way that products are actually designed. Finally, the paper presents new concepts, models and a structured procedure for Design for Quality that have evolved by looking at quality from the viewpoint of design methodology. Publication(s): Journal of Engineering Design, 1992, Vol.3, No. l. pp.63-80.
UW84
How to Get Lucky
by George Box, (June, 1992).
Some principles for success in quality improvement projects discuss, in particular, how to encourage the discovery of useful phenomena not initially being sought. A graphical version of the analysis of variance which can help to show up the unexpected is illustrated with two examples. Publication(s): Quality Engineering, 1993, Vol.5, No.3, pp.517-524.
UW88
What Can You Find Out From 12 Experimental Runs?
by George Box and Søren Bisgaard, (August 1992).
Report 78 has shown how 8 and 16 run two-level factorial designs could be used to study a number of factors. In particular they could be used to generate fractional factorial designs whose projective properties made them excellent screening designs for finding a few vital factors having major effects on a system. These fractional designs are particular examples of orthogonal arrays developed by Plackett and Burman which are available when N is a multiple of 4. In particular these authors derived such a design to study 11 factors in 12 runs. It turns out that this design has the remarkable property that it yields a full 23 factorial plus an additional optimal half replicate for any of the 165 choices of 3 factors out of the 11 factors tested. Publication(s): Quality Engineering, 1993, Vol.5, No.4, pp.663-668.
UW94
Graphical Aids to Measurement System Analysis
by John Hallinan and Søren Bisgaard (February 1993). Report In Progress
UW95
Spreadsheets for Analysis of Two-Level Factorials
by Søren Bisgaard (March 1993).
Analysis of two-level factorial and fractional factorial experiments can be performed very simply in a standard spreadsheet environment on a personal computer. This article shows a simple way to program Yates’ Algorithm for effects and the Reverse Yates’ Algorithm for predicting values and residuals. Publication(s): Quality Engineering, 1993, Vol.6, No.1, pp. 149-1 57.

AND
Iterative Analysis of Data from Two-level Factorials
by Søren Bisgaard (March 1993).
Thorough analysis of data from two-level factorial and fractional factorials can help engineers gain further
insight into the technical system under investigation. This article provides an example of how data can be analyzed iteratively to reveal the underlying structure of the data. An example by Taguchi is used to illustrate the iterative use of estimation residual analysis and transformations to model this data from an experiment on viscosity. Publication(s): Quality Engineering, 1993, Vol.6, No.2, pp.319-360.
UW97
Bringing Total Quality Improvement into the College Classroom
by W. Lee Hansen (March 1993).
This paper describes a recent effort to infuse the Total Quality Improvement (TQI) approach, popularized by Deming and others, into an upper-division, junior-senior economics course at the University of Wisconsin – Madison. The process of infusing TQI into instruction has received relatively little attention. Most efforts to bring TQI into higher education focus on improving administrative operations and establishing courses and programs for students to learn how to apply TQI in their future jobs. The challenge is in using TQI to help students realize their potential for learning in traditional courses.
UW98
A Review of Scientific Method for Setting Manufacturing Tolerances
by Paul R. Weiss (April 1993).
Several traditional and newer techniques for setting manufacturing tolerances are discussed. The traditional methods include worst case, statistical case, and proportional and constant factor scaling. Newer methods, such as Optimization and Monte Carlo Simulation are described more briefly. The Estimated Mean Shift model is included as a method for setting tolerances more realistically, while at the same time improving the communication between design and manufacturing departments. Additionally, some techniques are described for setting initial tolerances when little or no data or tables are available. Three tolerancing examples are included.
UW100
William G. Hunter: An Innovator and Catalyst for Quality Improvement
by George Box (June 1993).
This is the text of a talk given at the Speakers’ Dinner at the Sixth Annual William G. Hunter Conference on Quality in Madison, Wisconsin, on June 2, 1993. In it, George Box recalls Bill Hunter’s pivotal role in the birth of the quality movement in the city of Madison. Without Hunter’s catalytic contributions, Madison would not have its current leadership position in the improvement of quality in government, industry, and education.
UW101
Is Your Robust Design Product Robust?
by George Box and Conrad Fung (June 1993).
Robustifying a product is the process of defining its specifications to minimize the product’s sensitivity to variation. This article reviews two approaches to the problem of minimizing transmitted variation propagated from the product's components. The authors point out that no matter what approach is used, the solution can be extremely sensitive to certain assumptions which must be checked out. Sometimes tacit assumptions that seem innocuous turn out to be perilous. Thus we need to consider the robustness to assumptions of the robust design procedure itself. Publication(s): Quality Engineering, 1994, Vol.6, No.3, pp. 503-5 14.
UW102
Role of Statistics in Quality Control
by George Box (June 1993).
The role of Statistics in Quality Systems depends on certain philosophical issues which the author believes have been inadequately addressed. Three such issues are the role of statistics in the process of discovery, the extrapolation of results from the particular to the general, and the management climate in which quality improvement needs to be conducted. Statistical methods appropriate to discovery are discussed as distinct from those appropriate only to the testing of an already discovered solution. The manner in which the tentative solution has been arrived at is shown to determine with what assurance the experimental conclusions can be extrapolated to the practical application in mind. Whether or not statistical methods and training can have any impact depends on the system of management. A vector representation of management strategies is discussed. This can help to realign policies so that members of an organization can work together for its benefit. Publication(s): appeared as "Statistics and Quality Improvement" in the Journal of the Royal Statistical Society, Series A, 1994, 157, Part 2, pp.209-229.
UW104
Compensation and Employment Security
by Spencer Graves (June 1993).
Research by economists supports a couple of Japanese management practices that seem to have been under-emphasized in many Total Quality implementation efforts in the US – lifetime employment and linking pay to the accomplishments of the team. This paper illustrates the value of these policies with a few examples from consulting experience, then describes research by economists that suggests that the effects noted in the examples are commonplace and not isolated incidents. The focus is primarily on the link between management policies and productivity and profitability; this should make the conclusions largely independent of an understanding of the role of quality in organizational performance.
UW105
Total Quality Management and D*A*T Model
by Joe Van Matre (June 1993).
Total Quality Management (TQM) is the current embodiment of the quality movement that began at AT&T in the early 1930’s. Although initiated by Americans such as Walter Shewhart, W. Edwards Deming and Joseph Juran, it has been the Japanese who brought the quality movement to international attention. Japanese success in the global marketplace led their competitors to adopt similar strategies. In the United States, firms leading the way in TQM during the 1980’s were primarily manufacturers such as Motorola, Ford and Xerox. Their experiences coupled with the success of "Japanese management" employing American labor in Ohio (Honda), Kentucky (Toyota), Tennessee Nissan), and California (Sony), further increased the credibility of TQM as a major managerial development. Now many firms, service as well as manufacturing, are experimenting with and adopting the new philosophy. This paper reviews the essential elements of TQM (i.e., attitudes, tools and data) and proposes a conceptually simple but effective framework, the D*A*T model (Van Matre 1992), which focuses on those core elements and their interrelationships. Examples from the health care industry are used to show the role of TQM implementation in service industries. Publication(s): Journal of American Health Information Management Association, 1992, Vol.63, No.11.
UW108
Changing Management Policy to Improve Quality and Productivity
by George E.P. Box (August 1993).
It is generally accepted that the effectiveness of a quality improvement program often depends on changing the management culture in which it operates. Contemplated changes of policy affect different parts of an organization in different ways. A geometric representation of viewpoint on policy is introduced which makes it possible to compensate difficulties in making changes and finding effective ways to overcome them. Publication(s): Quality Engineering, 1994, Vol.6, No.4, pp.719-724.
UW109
Total Life Models – An Important Tool in Design of Quality
by Mikkel Mørup (December 1993).
Product quality is far more than "fitness for use" and robustness in the manufacturing process. This paper discusses the phenomena of product quality in the entire product life. It presents a total life model which serves several purposes, such as expanding the design teams' understanding of quality and adding structure to total life scenarios in the specification phase.
UW110
Quality and the Bottom Line
by Suren Bisgaard (December 1994).
Over the long term, Total Quality Management techniques must be validated economically or they will lose the support of management. In this article, a fictitious example is used to demonstrate how quality improvement tools can be applied to accounting data. These tools allow managers to make informed decisions about where quality improvement efforts will be most effective and show the resulting improvement in the bottom line. Publication(s): Quality Engineering, 1994-95, Vol.7, No.1, pp.223-235.
UW111
Discrete Proportional-Integral Control with Constrained Adjustment
by George Box and Alberto Luceño (February 1994).
It is well known that discrete feedback control schemes chosen to produce minimum mean square error at the output can require excessive manipulation of the compensating variable. Also very large reductions in the manipulation variance can be obtained at the expense of minor increases in the output variance by using constrained schemes. Unfortunately, however, both the form and the derivation of such schemes are somewhat complicated. The purpose of this article is to show that suitable "tuned" proportional-integral (PI) schemes in which the required adjustment is merely a linear combination of the two last observed errors can do almost as well as the more complicated optimal constrained schemes. If desired, these PI schemes can be applied manually using a feedback adjustment chart which is no more difficult to use than a Shewhart chart. Several examples are given and tables are provided that allow the calculation of the optimal constrained proportional-integral scheme and the resulting adjustment variance and output variance. Methods of tuning such controllers using Evolutionary Operation and experimental design are briefly discussed.
UW112
Orthogonal Design of Life Testing with Replacement: Exponential Parametric Regression Model
by Ilya Gertsbakh (March 1994).
This paper describes how to plan an ‘optimal’ life testing experiment when the lifetime is assumed to have an Exponential distribution. We further assume that the mean lifetime is equal to exp(b ₁x₁ +… +b _kx_k) where the covariates x, form an orthogonal Hadamard-type matrix which depends on testing conditions, and b ₁ are the
unknown parameters. n₀ devices are put on test. The period of testing, t₀, is divided into k stages of length t_i, i=1,…,k, and on each of these stages all devices operate under a fixed testing regime. (The number of different testing regimes, k ,equals to the number of parameters to be estimated). Each device which fails is immediately
restored and continues to operate. A closed maximum likelihood solution is given for estimates of b ₁ which exists if and only if at least one failure has been observed on each of the testing stages. Also the approximate optimal duration of the i-th testing stage, t_i*, which would provide the minimum of S AsVar [b _i] is derived. It is shown that the near-optimal testing policy is obtained when t_i* is proportional to the square root of the mean lifetime for the corresponding testing regime.
Finally, the expression for the Fisher information matrix is derived and the optimality criterion (which is the trace of its inverse) is expressed as a function of model parameters b _i the duration of testing stages t_i, and the number of devices operating on each of the testing stages.
UW113
Standard Errors of the Eigenvalues of Second Order Response Surface Models
by Søren Bisgaard and Bruce Ankenman (March 1994).
When second order response surface models involve more than three factors, confidence intervals for the eigenvalues of the second order coefficient matrix play an important role in the interpretation of their geometric shape. In this article, we propose a new method for estimating the standard errors, and thus confidence intervals of these eigenvalues. The method is simple in both concept and execution and involves the refitting of a full quadratic model to the data using the rotated coordinate system obtained from canonical analysis. The standard errors of the pure quadratic terms from this refitting are used to approximate the standard errors of the eigenvalues. Since it uses the canonical form as a basis, the method is geometrically intuitive and thus is easily taught. Our approach is intended to provide practitioners with quick estimates of the standard errors of the eigenvalues. In our justification of the method, we show that it is equivalent to using the delta method as proposed for this problem by Carter, Chinchilli and Campbell (1990).
UW114
The Impact of Measurement Error and Cost on Tolerancing a Single Dimension
by Søren Bisgaard and Spencer Graves (April 1994). Report In Progress
UW115
UW115
Common Principles of Quality Management and Development Economics
by Spencer Graves (May 1994). Report In Progress
UW119
Analysis of Factorial Experiments with Defects or Defectives as the Response
by Søren Bisgaard and Howard Fuller (June 1994).
The performance of a production process is often characterized by the number of defects in its products or the number of defective products. Typically, reduction of the number of defects or defectives is paramount to improving the quality of such a process. A powerful tool used for identifying variables that influence the process level of defects or defectives is experimental design. However, when using counts of defects or defectives as the experimental response the assumption of constant variance made with almost all standard analyses is violated. A common method for dealing with this problem is to transform the data before the analysis so that the assumption of constant variance is more likely. In this paper, we present various transformations that can be used to approximately stabilize the variance of counts of defects and the variance of proportion of defectives. We also re-analyze examples of each case where transformation of the experimental data followed by a simple analysis of the data led to significantly different conclusions. Publication(s): Quality Engineering, 1994-95, vol.7, No.2, pp.429443.
UW120
Assuring Product Success with ISO 9001?
by Gunhild Dalen (July 1994).
Several research projects have been conducted, and several reports and books have been written with the hope of finding the factors important for successful new product development. This article compares the portions of ISO9001 related to new product development with relevant research results. The conclusion is that ISO9001 is mainly concerned with the formal written documentation of the development process, the adherence to these documents, documentation of the result, and qualification of personnel and resources available to the project. But 1809001 does not include all the elements necessary for assuring a successful product development, such as customer contact, teamwork, consistent project team, authority of the team leader, or design for manufacturability.
UW123
Total Quality: Its Origins and Its Future by George Box (January 1995).
This article discusses how an efficient organization is characterized by its knowledge and learning capability. It examines the learning ability of the human animal, the logic of continuous, never-ending improvement, the catalysis of learning by scientific method, and Grosseteste’s Inductive-Deductive iteration related to the Shewhart Cycle. Total Quality is seen as the democratization and comprehensive diffusion of Scientific Method and involves extrapolating knowledge from experiment to reality which is the essence of the idea of robustness. Finally, barriers to progress are discussed and the question of how these can be tackled is considered.
UW128
On Robust Design in the Conceptual Design Phase – A Qualitative Approach
by Peder Andersson, (July 1995).
One of the most important contributions to quality engineering over the last decades is the concept of robust design and its accomplishment through the use of various experimental methods. However, the prerequisite parameter design in terms of a robust solution principle are seldom discussed and methods that aid robust design in the conceptual design phase are, to our knowledge, few. This article forwards the suggestion to use the principles behind the error transmission formula as a semi-analytic method for evaluation of robustness of concept solutions, prior to entering Taguchi’s parameter design stage.
UW129
Analysis of Unreplicated Split-Plot Experiments with Multiple Responses
by Marit Risberg Ellekjær, Howard T. Fuller and Kirsti Ladstein, (July 1995).
The purpose of this study is to demonstrate an effective strategy for unreplicated split-plot experiments with multiple responses. Through principal component analysis (PCA) the response variables are reduced to only those that describe different phenomena among the experimental samples. These selected response variables are then analyzed individually using ANOVA and Normal probability plots to identify the factors with the greatest influence on the quality and cost of the product. This approach makes it possible to take both the preferred quality characteristics and the production costs into account when studying a process or product. A case study from a fish food manufacturing company is used to illustrate our ideas.
UW130
Redesigning the Introductory Statistics Course
by Ronald D. Snee and Roger Hoerl, (July 1995). Report In Progress.
UW134
A Total Quality Improvement Approach to Student Learning
by W. Lee Hansen (October 1995). Report In Progress
UW137
Importance of Graphics in Problem Solving and Detective Work
by Søren Bisgaard (October 1996). Report In Progress
1996).
UW140
Nonstatistical Skills That Can Help Statisticians Become More Effective
by Ronald D. Snee (March 1996).
The T new economic era we live in has resulted in a variety of new work situations for statisticians. Many are asked to be a member of a team that involves several different functions of the organization. Statisticians are also asked to work with groups in non-technical areas. These groups tend to have less experience with data-based problem solving methods but, nonetheless, are working on problems critical to the success of the organization. Many statisticians have the opportunity to work with mid-and upper-level managers. All of these opportunities that require new skills and methods that can help statisticians become more effective are discussed. It is also shown how these new skills have much in common with statistical thinking.
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