How to critically analyse and evaluate.

Technical knowledge supports analysis

Strong analysis draws together relevant knowledge from across the course. When considering a product, the significance of a design decision may depend on its materials, properties, manufacturing processes, scale of production, CAD/CAM, accuracy, finishes, fixings, sustainability, safety and user requirements.

For example, a moulded polymer chair shell may suit high-volume production because, once expensive tooling has been made, the process can reproduce complex forms quickly and consistently. This can reduce unit cost at large volumes, but the initial tooling cost makes the same process less suitable for a small batch. The process is therefore not simply 'good' or 'bad'; its suitability depends on the production context.

What should be analysed?

• Function and fitness for purpose: whether the product reliably performs its intended task and under what conditions.
• User needs: ergonomics, anthropometrics, accessibility, comfort and ease of use, including differences between users.
• Aesthetics: how form, colour, texture and proportion suit the intended user and market rather than whether they are personally attractive.
• Materials: how properties enable the design, balanced against cost, processing, durability and environmental consequences.
• Manufacture: whether processes suit the geometry, material, required accuracy, production volume, assembly and cost.
• Safety: foreseeable hazards, misuse, failure and relevant standards.
• Sustainability: impacts across sourcing, manufacture, transport, use, repair, product life, disassembly and end-of-life rather than a single environmental feature.

Use evidence, not unsupported opinion

Evaluation should be supported by evidence such as user trials, dimensions, performance tests, questionnaires, observations, material tests or comparison with the design specification.

If testing shows that a handle causes discomfort, the useful analysis is why: for example, its diameter may be too small for the intended users, concentrating pressure on the hand. Increasing the diameter may improve comfort, but it could also increase material use or make the product harder for users with smaller hands to grip. A justified modification therefore considers the intended user group and is tested again.

Testing against a specification

Relevant specification points should be tested where possible. Quantitative criteria such as size, mass, load or time can be measured directly. Qualitative criteria such as comfort or appearance can use structured feedback from appropriate users.

The result only becomes useful evaluation when it is interpreted. Meeting one criterion does not necessarily mean the whole design is successful, and improving one feature can create a disadvantage elsewhere.

Balanced judgement and trade-offs

Design decisions usually involve competing requirements. A thicker component may increase strength but also increase mass, material use and cost. A sealed enclosure may improve water resistance but make repair and battery replacement harder. A lightweight composite may reduce energy use during transport or use but be difficult to separate and recycle at the end of its life.

A strong judgement therefore identifies which consequence matters most in the stated context and why. The same material, process or feature can be suitable in one product and unsuitable in another because the users, production volume, lifespan, cost or performance requirements are different.

Applying analysis to unfamiliar products

When analysing an unfamiliar product, begin with the evidence visible or given in the context and apply the technical knowledge that genuinely explains it. For example, do not assume a polymer part is injection moulded simply because it is plastic; look for evidence such as a complex one-piece form, consistent wall thickness, ribs, bosses, parting lines or ejector marks and consider whether the likely production volume would justify the tooling.

This produces analysis that is specific to the product rather than a list of memorised advantages and disadvantages.