The Voice of the Customer

TLDR: A self-selection bias in satisfaction measures used commonly for QFD and for corporate incentive programs is demonstrated, demonstrating how a product-development team used the voice of the customer to create a successful new product.

Abstract: In recent years, many U.S. and Japanese firms have adopted Quality Function Deployment QFD. QFD is a total-quality-management process in which the "voice of the customer" is deployed throughout the R&D, engineering, and manufacturing stages of product development. For example, in the first "house" of QFD, customer needs are linked to design attributes thus encouraging the joint consideration of marketing issues and engineering issues. This paper focuses on the "Voice-of-the-Customer" component of QFD, that is, the tasks of identifying customer needs, structuring customer needs, and providing priorities for customer needs. In the identification stage, we address the questions of 1 how many customers need be interviewed, 2 how many analysts need to read the transcripts, 3 how many customer needs do we miss, and 4 are focus groups or one-on-one interviews superior? In the structuring stage the customer needs are arrayed into a hierarchy of primary, secondary, and tertiary needs. We compare group consensus affinity charts, a technique which accounts for most industry applications, with a technique based on customer-sort data. In the stage which provides priorities we present new data in which product concepts were created by product-development experts such that each concept stressed the fulfillment of one primary customer need. Customer interest in and preference for these concepts are compared to measured and estimated importances. We also address the question of whether frequency of mention can be used as a surrogate for importance. Finally, we examine the stated goal of QFD, customer satisfaction. Our data demonstrate a self-selection bias in satisfaction measures that are used commonly for QFD and for corporate incentive programs. We close with a brief application to illustrate how a product-development team used the voice of the customer to create a successful new product.