The Systems Engineering Tool Box - Pugh Matrix (PM)

Contributor
Dr. Stuart Burge
Type Category
Instructional Materials
Types
Informative Text , Article
Note
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.

Reviews

Description

This article by Dr. Stuart Burge provides step-by-step directions on how to use a Pugh Matrix (also called a Pugh Chart, Pugh Method, and Decision Matrix). A Pugh Matrix is used by engineers to evaluate multiple design options based on a set of criteria. This article does not link to any particular content area, but would be appropriate for middle and high school teachers to learn about a systemic review process to support optimizing design solutions (as specified in the engineering disciplinary core ideas). It is therefore applicable to engineering problems in physical science, life science, or Earth science contexts. High school students could also use this article to learn about this decision making process, though it is likely too advanced for direct use by most middle school students.

Intended Audience

Educator and learner
Educational Level
  • Grade 12
  • Grade 11
  • Grade 10
  • Grade 9
  • Grade 8
  • Grade 7
  • Grade 6
  • Middle School
  • High School
Language
English
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

HS-ETS1-3 Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.

Clarification Statement: none

Assessment Boundary: none

This resource appears to be designed to build towards this performance expectation, though the resource developer has not explicitly stated so.

Comments about Including the Performance Expectation
The article doesn't specify that this process is being applied to a specific, complex real-world problem; it just notes a general process for evaluating and comparing solutions. High school teachers should thus ensure that they’re using this process in the context of such a problem (i.e., evaluating solutions to cleaning up the great Pacific garbage patch). It also doesn't specify a need to address particular constraints, as the performance expectation details. It leaves the determination of constraints or criteria up to those using the matrix. In engineering design, engineers are often given the constraints or criteria from clients, their boss or by the nature of the project, so depending on the project, teachers could specify these up front. But, it's also often beneficial for students to have the initial opportunity to come up with ideas for what criteria for success could be or what constraints they have to consider in evaluating solutions to a problem.

MS-ETS1-2 Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.

Clarification Statement: none

Assessment Boundary: none

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
The Pugh Matrix specifically provides a way to evaluate competing design solutions to a problem. This article focuses on looking at criteria for a successful design, but doesn't get into the idea of constraints. In the article, the author says that the first step is to identify the criteria, though no suggestion is given for how to go about this. The toaster example gives some insight but it isn't clear how to decide when you have identified a set of criteria that would be suitable for a particular design problem. To ensure that students consider constraints, teachers should help them identify both criteria and constraints in their analysis, putting both into the Pugh Matrix for consideration.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
A Pugh Matrix provides for weighting of the design criteria. There are several ways to do that. In this article the author suggests applying a multiplier from 1 to 5 to each criteria/constraint factor (see pg. 9. This weighting results in setting up priorities for which criteria are the most important in the design, and the designs best addressing those criteria thus receive more points. As another way to prioritize, instead of scoring each proposed on each design criteria with a ++, +, Same, -, or --, students (or the class or group) could give each design a numerical score. So, if an important criterion is safety, each design could be given a score from 1 to 5 on safety. Being out of 5 possible points shows it's an important criterion. If a less important criterion is cost, each design could be given a score from 1 to 3 points on cost, so with less possible points attributed for cost to the overall score, it would not be as prioritized. While prioritizing criteria and reviewing design performance in relation to these criteria are part of the Pugh Matrix process, optimization encompasses a bit more. In a lesson it will be important to emphasize the process of testing, revising and re-testing that would feed into the review of the performance of different designs in relation to criteria. The optimization process should likely also include selecting elements of various designs based on which better addresses different criteria and constraints. In the end, the design chosen may not be the one suggested by the Pugh Matrix due to other factors that come into play, such as a client just liking a design better. Notably, this article doesn’t address making tradeoffs, testing, revising, and retesting within the optimization process. Teachers should explicitly connect the Pugh Matrix process to results of testing competing design solutions, including test results as one of the design parameters incorporated in the matrix as appropriate. As solutions are revised and retested, new results would likewise be incorporated into this matrix. Tradeoffs will often come into play as a design is selected that scores well on some design criteria but not as well on others. A Pugh Matrix can thus inform reasoning for making tradeoffs.

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
The foundation for using a Pugh Matrix is to specify the criteria for a successful solution. This article does not emphasize the use of constraints in this process; however, whether or not a design meets necessary constraints might not always have a definite yes/no answer and could be weighted as well in this decision making process. This article doesn't come out and specify the use of this process for “real-world” problems because it's written for engineers and for educators who are going through actual design work related to real problems.

Disciplinary Core Ideas

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
Using a Pugh Matrix, as discussed in this article, students would take into account a range of constraints and criteria for their designs. However, this article does not go into depth on the possible constraints listed in this Core Idea (cost, safety, reliability and environmental impacts). In any design process it would be important to have students collaboratively come up with these constraints and include them in their design optimization process. Students should also be encouraged to consider "social, cultural, and environmental" impacts of their design solutions as they're determining the best solution.

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
Using a Pugh Matrix shows which design scored the best across the criteria. Therefore, students can combine parts of multiple designs to create the best overall score on meeting the criteria. This process is not an explicit part of this article. The article focuses more on deciding between options, though taking the best aspects of each option to optimize a final solution is a logical next step. Notably, just because an alternative has the best score on the Pugh Matrix, does not necessarily mean it is the optimal choice. Consideration must be given to constraints and other factors that may arise.

Crosscutting Concepts

This resource was not designed to build towards this crosscutting concept, but can be used to build towards it using the suggestions provided below.

Comments about Including the Crosscutting Concept
A Pugh Matrix could be thought of as modeling a set of design solutions. As is the case in science, models cannot represent every facet of a real-world phenomena. In the case of the Pugh Matrix, engineers do not consider every variable in the design solution or every possible criteria or constraint. The matrix thus becomes a model of the design solution, allowing multiple design solutions to be compared on an approachable and understandable number of facets.

This resource was not designed to build towards this crosscutting concept, but can be used to build towards it using the suggestions provided below.

Comments about Including the Crosscutting Concept
Though not explicit in the article, one of the criteria would ideally involve looking at the performance of the design. Finding patterns of superior performance of different design solutions will be an important part of determining which design is best. Testing and re-testing are standard parts of the design process.

Resource Quality

  • Alignment to the Dimensions of the NGSS: Using a Pugh Matrix as part of the optimization process--comparing how different designs meet criteria and constraints--will be a very useful addition to engineering extensions to science lessons. This article provides a good summary of how to use the Pugh Matrix to support that work. It connects well to two dimensions of the NGSS--the science and engineering practices and DCIs. Connections to cross-cutting concepts are suggested in this review, making this resource usable in a three-dimensional way.

  • Instructional Supports: This article is an instructional resource for teachers to understand a decision-making or design comparison process. It doesn't explicitly guide teachers in how they would use this process in a lesson with their students.

  • Monitoring Student Progress: This process doesn't really connect to monitoring student progress, though students' ability to use this process could be assessed. Supports for doing so are not provided.

  • Quality of Technological Interactivity: This process doesn't include technological interactivity, so supports for using technology are not provided here. A Pugh Matrix process could certainly be conducted by putting data and formulas into a spreadsheet, which could be useful for organization.