Collection of VOC data from multiple sources requires aggregation of the col- lected data and the analysis and prioritization of the major themes that custom- ers identify as necessary to meet their needs and value expectations. Organizing and prioritizing the VOC into themes requires the use of multifunctional teams using brainstorming and prioritization tools and methods. These prioritized themes will become the CTQs or high-level customer requirements that drive the internal specifications corresponding to the key process output variables (KPOVs) necessary to satisfy customers. Gaps in product or process performance require creation of new or modified products and services. Quality function deployment (QFD) is the structured methodology used to correlate CTQs into their specific design specifica- tions, i.e., KPOVs, or Y’s. QFD is also used to compare the required CTQs to those of current systems and identify performance gaps. In addition, QFD is useful in helping coordinate the work of a design team across organizational functions and facilitate competitive benchmarking activities. These characteristics ensure linkage of the VOC to an organization’s design and workflow systems. The QFD method- ology is embodied within the house-of-quality (HOQ) concept, which is shown in Figure 3.11. The HOQ is divided into sections or rooms that summarize data relevant to understanding how customer requirements, i.e., CTQs, are related to system elements of the product or service design. These system elements are sum- marized in the form of specifications, i.e., Y’s, that in aggregate satisfy the CTQ expectations of the customer as well as system key design input variables (KDIVs), i.e., X’s, which drive the levels of the Y’s in the product or service design. The goal of the CTQ to specification analysis is to ultimately develop quantitative relation- ships or models between the Y’s and their associated inputs, or X’s. The HOQ also allows the improvement team to see the interrelationships among several Y’s. This is useful when making trade-off decisions between various subsystems of the design. As an example, an automobile may be required to obtain high miles per gallon fuel ratings, but also have a minimum internal cabin volume for customer comfort. The QFD matrix or HOQ would show these interrelationships and allow design
trade-offs to be made by the team relative to weight that correlated to cabin volume. The Pugh matrix is a useful tool to evaluate product or service design trade-offs. An overview of the Pugh matrix method is shown in Figure 4.7. This evaluation method will be discussed in Chapter 4.
Section A of Figure 3.11 is used to list the prioritized CTQs obtained from the VOC analysis. The relative importance ratings are estimated using various priori- tization tools, including the AHP method, which will be discussed in Chapter 4. Modifications to these ratings can be made by considering Kano needs and the five value elements by market segment. In QFD literature these CTQs are called the what’s. In section B of Figure 3.11, the design requirements necessary to provide the CTQs are listed as clearly defined design specifications and translated into internal Y’s. These Y’s are often called the how’s. Section C of Figure 3.11 shows the correlations between each CTQ and the associated system elements, or the what’s as they relate to the how’s. A rating system of 1 to 10 is usually used to indicate weak (1), medium (5), and strong (10) correlations between the what’s and how’s. Competitive benchmarking is also used to aid the design analysis. This is shown in section D of Figure 3.11, in which competitive benchmarking enables a design team to understand how competitive designs meet the CTQ. Section E is used to evaluate relationships between one or more design elements, i.e., the how’s, because
System Design Requirements Competitor Ratings Specification Targets Analyze Performance Gaps Relationship Matrix Correlation Matrix Between Y and X Relationship 1 = Weak 5 = Medium 10 = Strong Specifications Gap
Importance Competitive Performance
Prioritize Themes in CTQs (Y’s) A C D B E F G
Understanding the Voice of the Customer (VOC) n 77
there may be conflicts among CTQs of different design elements, as mentioned earlier in the automobile example. The rating scale is 1 to 10. A 10 rating implies a high correlation between design elements, which could be positive or negative. Section F lists the specifications of each design element, i.e., Y’s. Several Y’s may be required to satisfy a specific CTQ. In section G, specifications are analyzed versus current design capability to identify performance gaps. Performance gaps may require that one or more projects be deployed to improve system performance. Alternatively, entire new system elements may have to be created by the team to satisfy some CTQs.
Service systems are also designed using the VOC and QFD methodology as well as process workflow models. Figure 3.12 shows a high-level system map called a SIPOC. SIPOC is an acronym representing the phrase supplier–input boundary– process–output boundary–customer. Relative to our current VOC discussion, the SIPOC is used to capture the prioritized list of CTQs for major process workflows. This information is used to correlate the CTQs to key operations and their system elements, i.e., the process and input X’s, and define the final process design. As the process design is iteratively created, the SIPOC becomes more detailed and quanti- fied until finally a system model is created to quantitatively describe the relation- ships of process inputs and outputs, i.e., Y = f(X). In many situations, this system model can be dynamically simulated and analyzed to ensure it meets its original design requirements as specified by the CTQs. These concepts will be discussed in Chapter 5 as well as subsequent chapters.