Concept evaluation and selection

While many stages of the design development process benefit from unbounded creativity and divergent thinking, concept selection is the process of narrowing a set of concept alternatives under consideration. Although concept selection is a convergent process, it is frequently iterative and may not produce a dominant concept immediately. Selection and evaluation are iterative processes that must be embedded in the development of new products. Designers are constantly evaluating which direction to take and generating many concepts to choose from.

A large set of concepts will usually be rapidly narrowed down to a more concise and focused set, but these concepts may need to be combined and improved to temporarily enlarge the set of concepts under consideration. Through several iterations a dominant concept finally emerges.

When selecting which idea(s) best satisfy the PDS, it is essential to remember that you may need to generate new concepts, modify existing concepts, or undertake further research to proceed. Selection should be a narrowing process, weeding out unsuitable ideas, rather than trying to pick the “best” idea. By referring back to the PDS and placing yourself in the user’s shoes through empathic design methods, you can help avoid selecting on a subjective personal basis.

Once an appropriate number of design concepts have been generated through sketching and modeling, you can refer back to the PDS and choose which concepts fulfil the criteria laid out in the original specification. To avoid subjectivity creeping into the decision-making process, it is best that all members of the design team perform this vital part of the process. If possible, input should also be included from the client and stakeholders, helping to evaluate the designs outlined from a number of perspectives. Explicit evaluation of the product with respect to manufacturing criteria improves the product’s manufacturability and helps to match the product with the process capabilities of the manufacturing company.

By adopting structured methods that can become a common language among the design team, from designers, engineers, manufacturers, and marketing staff, and beyond the team to users, clients, and buyers, the team can reduce ambiguity and confusion, create faster communication, and deliver products to market more rapidly.

Common evaluation and selection methods

All designers use some method for choosing a concept. The methods vary in their effectiveness and include the following:

• CAD models—Used to evaluate a design and its perceived use during the different stages of the design process.
• Checklists—Used to help define a product’s specification and identify users’ needs.
• External decision—Concepts are turned over to the customer or clients to determine the design selected.
• Interviewing prospective or actual users—Used to identify users’ needs and test the design against these needs.
• Intuition—The concept is chosen for its “feel,” with the designers relying on tacit knowledge rather than explicit criteria.
• Mock-up evaluation—Used to evaluate product usage with user’s participation.
• Multivoting—Each member of the design development team votes for several concepts. The concept with the most votes is selected.
• Product champion—An influential member of the product development team chooses a concept that determines the design direction.
• Pros and cons—The design development team lists the strengths and weaknesses of each concept and makes a choice as a group.
• Protocol analysis—Used to evaluate a design and understand the users’ concept of the product. A verbal and/or video recording of a user undertaking a task is made to gain more understanding of the activity.
• Prototype and test—The design team builds and tests prototypes of each concept to verify a design under “real” conditions, making a selection based upon test data and set criteria.
• Task analysis—An approach used to define and evaluate the operational procedures of a product.
• Matrix evaluation—Also known as the Pugh method, matrix evaluation is a quantitative technique used to rank designs against set criteria.

Conclusion

As we have seen, the manner, style, and procedure in which an individual designer or design team develop a design can often be quite distinctive and personal. It is necessary for a designer, therefore, to be able to present his or her development work so that he or she can easily communicate with others within and outside the design team. Documenting the decision-making process enables the creation of a readily understood archive of the rationale behind concept decisions. Such a report is useful for assimilating new team members and for quickly assessing the impact of changes as the product moves through detail design toward the next stage of the design process—manufacture and the marketplace—covered in the following chapter.