Decision-matrix method

The decision-matrix method, also calls Pugh method, Pugh Concept Selection is a quantitative technique use to rank the multidimensional options of an option set. It is frequently use in engineering for making design decisions but can also be use to rank investment options, vendor options, product options or any other set of multidimensional entities. The design concept for Pugh Method should be pass the absolute filters. There are some filters that should be pass which are:

• Evaluation base on judgment of feasibility of the design. It is include the overall evaluation of the design team as to the feasibility of each concept


• Evaluation base on assessment of technology readiness.


• Evaluation base on go/no-go screening of the customer requirements. After pass the filters 1 and 2, the emphasis shifts to establishing whether it meets customer requirement frame win the QFD and the PDS.

Pugh Concept Selection Method is a quantitative technique use to rank the multidimensional options of an option set. It is frequently use in engineering for making design decisions but can also be use to rank investment options, vendor options, product options or any other set of multidimensional entities.

Basic about decision matrix method

A basic decision matrix consists of establishing a set of criteria upon which the potential options can be decompose, score, and sum to gain a total score which can then be rank. Importantly, the criteria are not weight to allow a quick selection process.

A basic decision matrix consists of establishing a set of criteria upon which the potential options can be decompose, score, and sum to gain a total score which can then be rank. Importantly, the criteria are not weight to allow a quick selection process.

Advantages of Pugh Methods

• Finding a “best” design


• Prevents a team from “falling in love”


• With a flaw design or one not meeting


• All design constraints or objectives


• Communication tool; builds consensus


• Base on the “voice of the customer”


• Results in significant cost savings

The advantage of this approach to decision making is that subjective opinions about one alternative versus another can be made more objective. Another advantage of this method is that sensitivity studies can be perform. An example of this might be to see how much your opinion would have to change in order for a lower rank alternative to out rank a competing alternative.

The Pugh Evaluation Process

Phase I

1. Criteria: The list of evaluation criteria is develop through team discussion. A benchmark or datum is select, usually the “best” existing product. If no comparable product exists, one of the new concepts (select at random) can serve as datum.


2. Design concepts: Original design concepts are brainstorm by individual or small teams.


3. Evaluation matrix: Each design concept is discuss and evaluate against the datum. Through the discussion, new concepts emerge; they are need to the matrix and evaluate.


4. Round 1 result: The result of the first round is evaluate, and the top ranking concept is select as the datum for the next round. During an incubation period, the teams improve the original design concepts by borrowing ideas and components from each other, as well as through additional creative thinking. Then Steps 3 and $ are repeat with these improve, synthesize designs.

Phase II

5. Better designs: The weakest design is drop; the improvement process is continue for additional round with fewer but increasingly better concepts. During the process, the strong, surviving concepts are engineer to more detail; the criteria are expand and further refine. The weak point of the concepts is being eliminate. The team gains insight into the entire problem and solution.


6. Superior concept: the process converges to strong consensus concepts that cannot be overturn by a “better idea’. The team is commit to this superior design and wants to see it succeed.

These are the list of design of cup.

A= Styrofoam cup

B= injection-mold cup with a handle.

C= paper cup with a cardboard sleeve.

D= paper cup with a pull-out handle.

E= paper cup with a cellular wall.

Concept Selection (Evaluation)

Concept selection is one of the most critical decision-making exercises in a product development. To make decisions effective, one must basically carry out two steps.

• Minimize the possibility of misrepresenting a solution that may be effective.


• Engineer is not familiar with the technology.


• Fully consider the different ramifications of a decision.

For example, not considering the costumer’s need may lead to the product failing in the marketplace.

• Design Evaluations: Occurs at all phase of product evaluation, from concept to detailed design phases. Structured decision-making methods are need.


• Quality of Information:Low quality of information- how well each alternative design would meet criterion cannot be fully understood. High quality of information- the alternative solutions is well understood.


• Technology Readiness Assessment: If a technology is to be used as part of a product design, it must be mature enough that its use is a design issue, not a research issue.

Engineering characteristic that should be on the cups:

• Temperature in the hand


• Temperature of the outside of the cup


• Material environmental effect


• Indenting force of cup wall


• Porosity of cup wall


• Manufacturing complexity


• Ease of stacking the cup


• Ease of use by customer


• Temperature loss of coffee over time


• Estimated cost for manufacturing the cup in large quantities

After the discussions our group decide to eliminate the design concept  D since it has poor temperature condition compare to the Styrofoam cup (datum). It also has more complex shape and not easy to use by the customer compare to the Styrofoam cup.

Then in order to choose the best design we move to the second Pugh Chart by using design concept B as our new datum since it has the highest number of positives.

B= injection-molded cup with a handle.

C= paper cup with a cardboard sleeve.

E= paper cup with a cellular wall.

MECHANISM OF THE PUGH’S CONCEPT:

It is implemented by establishing an evaluation team, and setting up a matrix of evaluation criteria versus alternative embodiment's. This is the scoring matrix usually associated with the QFD method and is a form of prioritization matrix. Usually, the options are scored relative to criteria using a symbolic approach (one symbol for better than, another for neutral, and another for worse than baseline). These get converted into scores and combined in the matrix to yield scores for each option.

• Effective for comparing alternative concepts


• Scores concepts relative to one another


• Iterative evaluation method


• Most effective if each member of a design team performs it independently and results are compared.


• Comparison of the scores generated gives insight into the best alternatives.

Each concept must be compared to the customer requirements in an absolute fashion. Each customer need must be transformed into a question to be addressed to each concept. The questions should be answerable as either yes or maybe (go), or no (no-go).This evaluation will weed out concepts quickly and will help generate new ideas.

CONCEPT SELECTION (PUGH’S METHOD)

Based on the Decision-Matrix (Pugh’s method), this method is very effective for comparing concepts that are not refined enough for direct comparison with the engineering requirements.

The method is an iterative evaluation that tests the completeness and understanding of requirements, quickly identifies the strongest concept.

The method is most effective if each member of the design team performs it independently. The results of the comparison will usually lead to repetition of the method, with iteration continued until the team reaches a consensus.

Step to Construct / Design Pugh Matrix

Choose or develop the criteria for comparison.

Examine customer requirements to do this. Generate a set of engineering requirements and targets.

Select the Alternatives to be compared.:

The alternatives are the different ideas developed during concept generation. All concepts should be compared at the same level of generalization and in similar language.

Generate Scores.:

Usually designers will have a favorite design, by the time it comes to pick one. This concept   can be use as datum, with all the other being compare to it as measure by each of the customer requirements. If the problem is to redesign an existing product, then the existing product can be use as the datum.

For each comparison the product should be evaluate as being better (+), the same (S), or   worse (-). Alternatively, if the matrix is develop with a spreadsheet like Excel, use +1, 0, and 1 for the ratings. If it is impossible to make a comparison, more information should be develop.

Compute the total score

Four scores will be generate, the number of plus scores, minus scores, the overall total and the weight total.

•     The overall total is the number of plus scores- the number of minus scores.


•     The weight total is the scores times their respective weighting factors, add up.


•     The totals should not be treat as absolute in the decision making process but as guidance only.


•     If the two top scores are very close or very similar, then they should be examine more closely to make a more inform decision.

Variations on scoring:

A number of variations on scoring Pugh’s method exist. For example a seven level scale   could   be use for a finer scoring system where:

•     +3 meets criterion extremely better than datum


•     +2 meets criterion much better than datum


•     +1 meets criterion better than datum


•       0  meets criterion as well as datum


•     -1  meets criterion not as well as datum


•     -2  meets criterion much worse then the datum


•     -3  meets criterion far worse than the datum

The advantage of this approach to decision making is that subjective opinions about one alternative versus another can be made more objective. Another advantage of this method is that sensitivity studies can be perform. An example of this might be to see how much your opinion would have to change in order for a lower rank alternative to out rank a competing alternative.

SUMMARY

• Estimation is a critical skill to develop and can help in quickly eliminating weak concepts


• The feasibility of the concepts is base on the design team’s knowledge. It is often necessary to augment this knowledge with research and development of simple models.


• In order for a technology to be use in a product, it must be ready.


• A go/no-go screening base on customer needs helps to eliminate some of the concepts quickly.


• The decision matrix (Pugh’s method) provides means of comparing and evaluating concepts. The method gives insight into strong and weak areas of the concepts.