Engineering MakingMany Ideas, One Smart Choice: Brainstorm and Compare with a Decision Matrix
Atlas the engineer-explorer stands at a bright workshop whiteboard, marker in hand, circling the highest row total in red on a hand-drawn decision matrix that scores three phone-case ideas against safety, cost, and ease-of-carry criteria.
- Generate at least three different possible solutions to a design problem before judging any of them
- Distinguish a criterion (a goal the solution should meet) from a constraint (a limit it must stay inside)
- Score competing solutions in a decision matrix using a consistent rating scale
- Choose the best solution by comparing the summed scores from the decision matrix instead of picking a favorite
Key terms
- Brainstorming
- Generating many possible ideas freely without judging them yet
- Criterion
- A goal a design should meet well, used to score solutions
- Constraint
- A hard limit a design must not break to be allowed
- Decision matrix
- A scoring grid that rates each idea against each criterion
Diverge Before You Converge
Engineers deliberately separate inventing ideas from judging them. During the diverge phase you chase quantity and variety, writing every idea down even the silly ones, because a wild idea often sparks a workable one. Only after you have a rich list do you converge, narrowing toward the strongest option. Judging too early kills the very ideas that lead somewhere new.
Screen, Then Score
Comparison happens in two steps. First screen: throw out any idea that violates a hard constraint, because no amount of cleverness rescues a solution that is not allowed. Then score the survivors in a decision matrix. Using one consistent rating scale for every idea on every criterion is what makes the comparison fair rather than a popularity contest, and the summed totals give you a defensible reason for your final pick.
Worked examples
Three phone-case ideas are scored 1 to 3 on safety, cost, and carry. Foam Wrap scores 3, 2, 1; Hard Shell scores 2, 3, 2; Sleeve scores 1, 1, 3. All fit the constraints. Which wins?
- Add Foam Wrap's row: 3 + 2 + 1 = 6.
- Add Hard Shell's row: 2 + 3 + 2 = 7.
- Add Sleeve's row: 1 + 1 + 3 = 5.
- Compare totals: 7 is the highest, so Hard Shell is the strongest overall choice.
Answer: Hard Shell, with the highest total of 7.
Activity
Put these four engineering design step cards in the correct order from first to last
Practice
List three different ideas for a device that keeps an umbrella from dripping indoors.
Pick two criteria and one constraint for a reusable water bottle, then explain your choices.
Common mistakes to avoid
- The first good idea is the one to buildGenerating and comparing several options usually reveals a stronger solution than committing to the first idea.
- A constraint and a criterion are the same thingA constraint is a pass-or-fail limit, while a criterion is a ranked goal that measures how good a design is.
Check your understanding
Your design must cost less than $10 to build. What is '$10 maximum' an example of?
Why do engineers brainstorm several ideas before using a decision matrix?
In a decision matrix where every criterion counts equally, Idea A scores 7 total, Idea B scores 9, and Idea C scores 5. Both A and B fit all constraints. Which should you choose and why?
Recap
Engineers brainstorm many ideas without judging, eliminate any that break a hard constraint, then score the survivors in a decision matrix using one consistent scale and pick the highest total as evidence for their choice.
Reflect
Think of a recent choice you made by gut feeling. How might a decision matrix have changed it?