Sensitivity Analysis of the Rating Scales and Worth Calculation Schemes Used in QFD Matrices


Quality Function Deployment (QFD) is matrix method that identifies relative worth of product requirements from the customer requirements and their importance. Understanding the relative worth enables engineers to evaluate the potential of design concepts to achieve important requirements. In a QFD matrix called "House of Quality" or QFD I, engineers assess correlations between product requirements and customer requirements using a linear (e.g., 1-3-5) or an exponential (e.g., 1-3-9) rating scale. The exponential scale assigns product requirements that have large correlations with customer requirements a higher ratings of 9 instead of 5, and therefore, gives them larger relative worth. This paper studies how the choice of linear 1-3-5 and exponential 1-3-9 rating scales changes the relative worth of product requirements. To avoid being restricted to any specific pattern of a QFD matrix, this paper uses simulations and analytic approaches to obtain distributions of changes of relative worth, and to calculate the upper bounds of these changes. Finally, in an illustrative example, the authors integrate QFD and concept evaluation activities and provide a case in which the choice of rating scale in a QFD I matrix changes the optimal concept.


Mechanical and Aerospace Engineering

Keywords and Phrases

Concept Selection; QFD; Rating Scale; Sampling with Replacement; Sensitivity Analysis; Quality function deployment

Document Type

Article - Conference proceedings

Document Version


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© 2004 American Society of Mechanical Engineers (ASME), All rights reserved.

Publication Date

01 Jan 2004

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