Concept Selection

Methods for choosing a concept

In general, the design and development process benefit from divergent thinking and unbounded creativity. Eventually, a selection must be made. Concept selection is a process of narrowing the concepts under consideration, and is thus a convergent process.

A (potentially) large set of concepts is reduced to a "short list" - but the short list may contain combined concepts. Here are some selection methods:

The concept selection process we will use is built around the use of decision matrices.

Concept Screening

Screening matrix

The concept screening process consists of six parts:

• Preparing the selection matrix
• Rating the concepts
• Ranking the concepts
• Combining and improving the concepts
• Selecting one or more concepts
• Reflecting on the results and process

In preparing the selection matrix, which is a simplified version of a KT matrix, also known as a Pugh Matrix, the following steps are taken:

• List the project concepts as columns of the matrix
  • If necessary, reduce the list to a manageable number by the multivote procedure
• List the selection criteria as rows of the matrix
  • Pick criteria based on customer needs, or enterprise needs
  • The criteria must all have the same weight
• Choose a reference concept

In rating the concepts, do the following

• Place a relative score of (+), (0), or (-) in each box by making a comparison with the reference concept
• Use objective metrics as the basis for the rating when possible

In ranking the concepts, the team sums up the pluses and minuses for each concept, and then rank orders the concepts. The team then examines the results of this process and should ask:

• Is there a good concept that has been degraded by one bad feature? Can this concept be improved with a minor modification?
• Are there two concepts that can be combined to produce a superior one?

Now the team selects a few concepts as the ones that show the most promise and gets ready to move forward to the concept scoring process, by reflecting on the screening process: Is the team comfortable with its selection?

Concept Scoring

Scoring matrix

The concept scoring process consists of five parts:

• Preparing the scoring matrix
• Rating the concepts
• Ranking the concepts
• Selecting one or two concepts
• Reflecting on the results and process

The scoring matrix resembles a KT matrix and is more detailed than the screening matrix. The following steps are taken:

• List the remaining project concepts as columns of the matrix
• Split the concept columns into two - one for rating and another for weighted scoring
• List the selection criteria as rows of the matrix
  • The criteria may be more detailed than those used in the screening matrix - that is, you may now use secondary and tertiary needs.
  • Now, add weights to the criteria - use team consensus to determine these weights.
• Choose a reference concept.

In rating the concepts, do the following:

Place a numerical score of 1, 2, 3, 4, or 5 in each box by making a comparison with the reference concept, where

1. Much worse than reference
2. Worse than reference
3. Same as reference
4. Better than reference
5. Much better than reference

In ranking the concepts, the team multiplies the criteria weight by the relative performance rating for each component, and then ranks the concepts by total score.

Now the team selects one or two concepts as the ones that show the most promise and gets ready to move forward to prototyping. The team should reflect on the scoring process because this may now be the "point of no return."

There are several points that deserve further consideration:

• Subjective criteria are hard to assess and evaluate. Opinions of people outside of the team can be very valuable here.
• Objective criteria seem relatively easy to evaluate - but is the overall quality of a particular concept simply equal to the sum of performances in all selection criteria? There can be non-linear relationships among various selection criteria.