Quality function deployment (QFD) is a “method to transform user demands into design quality, to deploy the functions forming quality, and to deploy methods for achieving the design quality into subsystems and component parts, and ultimately to specific elements of the manufacturing process.”1
QFD is designed to help participants focus on characteristics of a new or existing product or service. QFD helps transform customer needs (the "voice of the customer" [VOC]) into design characteristics (and appropriate test methods) for a product or service, prioritizing each product or service characteristic while simultaneously setting development targets for product or service.
A QFD is begun by the team generating the intended customers' vital few expectations, preferably with customer input or participation. Each of those customer expectations is rated from 1 to 5 in importance. The team next lists the attributes that contribute to the customer expectations – the "hows," or product requirements. The impact of each "how" on each customer expectation is rated either high, medium, or low (or left blank if there is no relationship). Using a scale wherein each "high" impact is worth 9, each "medium" worth 3 and each "low" worth 1, the sum of the products of that impact score and the associated expectation importance score can be found. The relative importance of each product requirement can then be shown by graph. Likewise, the sum of products across each customer expectation indicates the relative importance actually being placed on that expectation.
Each of the product requirements can be broken down into successive levels of QFDs, though we generally recommend addressing only the most critical of those due to the complexity multi-level QFDs can quickly generate.
QFDs should always be done by a team with broad knowledge of the product requirements. To avoid the typical drudgery of participants arguing over the score of each factor, we have developed and use a method that allows everyone input electronically. The facilitator then releases all the scores to the participants, who can ask the reason behind a score that may appear to be an outlier. Outliers are often due to someone with critical additional knowledge that would otherwise be dismissed.
Note 1: Akao, Yoji. "Development History of Quality Function Deployment". The Customer Driven Approach to Quality Planning and Deployment. Minato, Tokyo 107 Japan: Asian Productivity Organization. pp. 339. ISBN 92-833-1121-3.