Evaluating a product: users, professionals and new technology
Design & Technology · Key Stage 3 · The School
Testing against the specification
A specification is a list of things the product must do. It is written before making starts. A good one is written so that each point can be tested. Compare two points. It should be strong cannot be tested, because nobody can say when you have got there. It must hold 2 kg without bending for good tells you exactly what to do. Now the check becomes a simple table: the point, the test, the result, and met or not met. When a point fails, write down by how much. Falling short at 1.8 kg is a small problem. Falling short at 0.4 kg is a different one.
Evidence from users
A USER TRIAL tells you things a workshop test cannot. Give the product to people in the place it is meant for, and watch. Time how long the task takes. Count how many tries it needs. Note where people stop and think, and what they get wrong. Asking do you like it gets you politeness. Watching someone fail to open a pack three times gets you a design change. If you do ask a question, ask about the task they have just done, not about the product in general.
Learning from professionals
Designers study the work of other designers, old and new, to widen what they think is possible. Dyson tested a cyclone through thousands of models before it worked. The Anglepoise lamp uses springs so it holds any position you put it in. OXO Good Grips began with one person with arthritis, and ended with handles that suit everybody. For each one, ask three questions. What problem was it solving? What did the designer change? What did that cost, in money, in materials, or in something the product now does worse?
New technology changes what a product can be. A designer has to judge the trade. 3D printing makes one-off and complex shapes cheap, but making many of the same part that way is dear. Sensors let a product respond to what is around it. They also add a battery, one more thing to go wrong, and a question about privacy. Smart materials such as shape-memory alloys can do the job of a mechanism, which cuts the number of parts and puts the price up. So the question is never is this modern. It is this: does the change move the product closer to its specification, and what does it give up to get there?