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19

Economical Experimentation via

‘Lean Design’

T. N. Goh

In industrial applications of design of experiments, practical constraints in resources
such as budget, time, materials and manpower could lead to difficulties in completing
an experiment even of moderate size. This problem can be addressed by an approach
referred to as ‘lean design’, with which no more than a bare minimum number of
response values are required, and the results of a lean design experiment can be
improved incrementally up to a point identical to what can be obtained from a regular
design. A numerical example illustrates both the principles and applications of this
cost-effective approach to experimentation.

19.1 INTRODUCTION

Design of experiments as a means of understanding cause-and-effect relationships
among the controllable factors of a process and response characteristics is now an
established quality improvement tool in industry. In the past fifteen years, design of
experiments has also been integrated with ideas of quality engineering for product
and process design, first advocated through what have become popularly known as
Taguchi methods. 1,2 Although there have been disagreements over the efficacy or
even validity of Taguchi methods, 3−5 the debates have brought about a widespread
awareness of a variety of issues related to the application of experimental design
in real life; examples of design considerations are type of design (number of levels;
what fraction of a factorial to use; resolution of effects), structure of design (taking

This chapter is based on the article by T. N. Goh, ‘Economical experimentation via “lean design”’, Quality
and Reliability Engineering International, 12, 1996, pp. 383--388, and is reproduced by the permission of the
publisher, John Wiley & Sons, Ltd
Six Sigma: Advanced Tools for Black Belts and Master Black Belts L. C. Tang, T. N. Goh, H. S. Yam and T. Yoap
C 2006 John Wiley & Sons, Ltd
297