Selecting a solution

If you have several potential solutions, how do you pick the best solution(s) for implementation? What factors would you consider to evaluate the solutions? Is there a structured approach to selecting the best solutions? How can we convince others that we have chosen the best solution(s)?

Pugh Analysis

Design for Six Sigma (DFSS) has a number of tools that improve the speed and quality of decisions. Pugh analysis is a decision-support tool that facilitates selecting a solution by helping in evaluating, rating, and comparing different alternatives against multiple criteria. The method was developed in the 1980s by Stuart Pugh, a professor of engineering at the University of Strathclyde in Glasgow, Scotland. The goal of Pugh analysis is to facilitate rational decision making by evaluating alternatives using different criteria.

In DFSS, a Pugh decision matrix – also known as a decision or analysis grid – is particularly useful for ranking alternative solutions against predetermined criteria derived from the voice of the customer (VOC). It’s also important for documenting decisions to ensure that stakeholders will be able to understand the reasoning behind your decisions.

Pugh analysis uses a matrix-based process to make it easier to systematically weigh the pros and cons of each design alternative relative to your criteria. The matrix consists of a list of alternatives, also called options or solutions, on one axis. On the other axis is a list of criteria, or requirements. The matrix also indicates how the alternatives for each criterion will be weighted in comparison to a baseline.

Generating alternative design concepts is the starting point for Pugh analysis. To do this, Six Sigma practitioners use tools such as Quality Function Deployment and TRIZ to produce viable alternate concepts that meet the requirements of the project or initiative, and can be used in the Pugh matrix.

A Pugh analysis is performed iteratively. Using the matrix, stronger concept alternatives are retained and weaker ones are eliminated until an optimal concept is reached. If a clear winner is not identified, new concepts are generated. Concepts can be reconfigured, merged, or refined to distinguish options from each other. Then the analysis is repeated until one best solution is clear.

The steps of Pugh analysis – Pugh analysis can be implemented in six steps:

• choose the alternative concepts and criteria
• choose a baseline concept
• rate each concept relative to each criterion
• sum the scores and choose the best concept
• develop improved alternative concepts
• iterate the process

Pugh analysis is an excellent tool for Six Sigma teams because the best solution to an issue may not be obvious to everyone, or may be the source of conflicting opinion. Because it eliminates subjective comparisons, Pugh analysis gives team members a holistic view of issues and helps them resolve differences.

The rating scale that you use in a Pugh analysis is based on a predetermined numerical scale. The extent of the scale is a choice made by the Six Sigma team. It will be determined by the complexity of the analysis. A simple analysis could consist of a Yes or No.

Applying Pugh analysis – There are a number of different ways of constructing a Pugh matrix. The rating scale used is an arbitrary decision. You’ll have to decide on the number of increments in your scale, and on the significance of each increment.

Some teams prefer to give each criterion a weight based on its importance to the project. The predetermined weight for each criterion is multiplied with the scores given to each alternative to give a more precise result with regard to each concept. This is more effective in a situation where criteria are not equal in stature.

Some teams prefer to use a positive rating scale, for example from one to five. Also, some scales can be used independently of a baseline. The choice of scale will depend on what is efficient and effective for the project. Some scale types are the plus or minus scale; best to worst scale; high, medium, low scale; or yes or no scale.

Pugh analysis is an excellent tool for making design decisions, but it can also be used to rank investment opportunities, vendor options, product features, or any other set of multidimensional entities. Its value is that it provides something to measure against, so that you can discover whether or not you are making the decisions that will allow you to achieve your goals.

A Pugh decision matrix allows decision makers to structure, and then solve their problem. This is done by specifying and prioritizing needs with a list of criteria; evaluating, rating, and comparing individual solutions; and selecting the best solution based on the cumulative ratings. The six steps in a Pugh analysis are to choose the alternative concepts and criteria, choose a baseline concept, rate each concept relative to each criterion, sum the scores and choose the best concept, develop improved alternative concepts, and iterate the process.

Solutions Selection Matrix

A Solutions Selection Matrix is a matrix helping to identify the best solution(s) among several solutions identified, by weighting the impact of each solution on the CTQs (Critical To Quality) and cost-benefit, hence measuring the effectiveness of solving the problem.

A Solutions Selection Matrix allows to:

• select the most adapted option among solutions that cannot be concurrently implemented
• weight the impact of each option on resolving the problem

A solution selection matrix will contain the following:

• The problem we’re trying to solve.
• The root causes attached to the problem, in a sideways branching tree diagram.
• The practical solutions attached to each root cause – a root cause can have several practical solutions.

It can be completed with the following steps:

• List all the criteriae that should impact decision making (cost, CTQs…)
• Attribute a weight to each criteria, representing its importance in reaching the expected end state
• List all the solutions proposed to reach the objectives
• Score the impact of each solution listed in step 3 on each criteria listed in step 1
• Multiply the score (step 4) by the weight attributed to each criteria (step 2)
• Compute the total score of each solution by summing the weighted scores obtained in step 5
• If only 1 solution must be selected, assess the meaning of choosing the solution with the highest total score in the business context and revisit the conclusion if needed; if several solutions can be selected, prioritize their implementation from highest to lowest total score.

SCAMPER Tool

SCAMPER is a mnemonic that stands for:

• Substitute
• Combine
• Adapt
• Modify
• Put to another use.
• Eliminate
• Reverse

You use the tool by asking questions about existing products, using each of the seven prompts above. These questions help you come up with creative ideas for developing new products, and for improving current ones.

Alex Osborn, credited by many as the originator of brainstorming, originally came up with many of the questions used in the technique. However, it was Bob Eberle, an education administrator and author, who organized these questions into the SCAMPER mnemonic.

First, take an existing product or service. This could be one that you want to improve, one that you’re currently having problems with, or one that you think could be a good starting point for future development.

Then, ask questions about the product you identified, using the mnemonic to guide you. Brainstorm [Add to My Personal Learning Plan] as many questions and answers as you can. (We’ve included some example questions, below.)

Finally, look at the answers that you came up with. Do any stand out as viable solutions? Could you use any of them to create a new product, or develop an existing one? If any of your ideas seem viable, then you can explore them further.

Substitute

• What materials or resources can you substitute or swap to improve the product?
• What other product or process could you use?
• What rules could you substitute?
• Can you use this product somewhere else, or as a substitute for something else?
• What will happen if you change your feelings or attitude toward this product?

Combine

• What would happen if you combined this product with another, to create something new?
• What if you combined purposes or objectives?
• What could you combine to maximize the uses of this product?
• How could you combine talent and resources to create a new approach to this product?

Adapt

• How could you adapt or readjust this product to serve another purpose or use?
• What else is the product like?
• Who or what could you emulate to adapt this product?
• What else is like your product?
• What other context could you put your product into?
• What other products or ideas could you use for inspiration?

Modify

• How could you change the shape, look, or feel of your product?
• What could you add to modify this product?
• What could you emphasize or highlight to create more value?
• What element of this product could you strengthen to create something new?

Put to Another Use

• Can you use this product somewhere else, perhaps in another industry?
• Who else could use this product?
• How would this product behave differently in another setting?
• Could you recycle the waste from this product to make something new?

Eliminate

• How could you streamline or simplify this product?
• What features, parts, or rules could you eliminate?
• What could you understate or tone down?
• How could you make it smaller, faster, lighter, or more fun?
• What would happen if you took away part of this product? What would you have in its place?

Reverse

• What would happen if you reversed this process or sequenced things differently?
• What if you try to do the exact opposite of what you’re trying to do now?
• What components could you substitute to change the order of this product?
• What roles could you reverse or swap?
• How could you reorganize this product?