IB Design Technology SL — All Flashcards

The relationship and interaction between people (aspects of the human body) and the products, systems and environments they use.

It makes a design more efficient, more usable, more functional, more effective and safer.

Comfort is only part of the people–product fit. A comfortable product can still fail the environment it is used in — for example a screen that is unreadable in sunlight.

The measurement of human physical dimensions, expressed as a percentile range, which presents the spread of physical characteristics across a population.

Static (structural) is measured with the body still — sitting eye height, popliteal height. Dynamic (functional) is measured while the body moves — forward grip reach, arm sweep.

Age, gender, ethnicity and disability. The age of the dataset itself matters too — populations have grown taller over recent decades.

The vertical distance from the floor to the underside of the knee when seated. It sets seat height, so that a user's feet rest flat and their thighs are not compressed.

The value below which a given percentage of a population falls. The 5th percentile of reach means 5% of people reach less far than that.

Reach is set from the SMALLEST user (5th percentile); clearance is set from the LARGEST user (95th percentile).

It fails half the population by construction, and nobody sits at the 50th percentile in every dimension at once. It suits only dimensions where being wrong either way is harmless.

90% of the user population. Covering the last 5% at each extreme usually costs far more in mechanism and tooling than it gains in users, so it is excluded as a stated decision.

Designing the product to be adjustable, and producing it in a range of fixed sizes. Many products use both.

Advantage: one product covers the whole 5th–95th range with one set of tooling. Disadvantage: the mechanism adds cost and weight, can fail, and only helps if the user actually adjusts it.

Advantage: each item is simpler, lighter and cheaper, with nothing to break. Disadvantage: several sets of tooling and stock, and the user must pick the right size.

A cycle helmet: two or three shell sizes keep each one light, and an adjustable cradle closes the remaining gap — a loose helmet does not protect in a crash.

The three-dimensional space a user can reach without moving from their position. Everything the product asks them to touch must lie inside it.

Normal reach is swept with the upper arm at the side and only the forearm extended — for constant and safety-critical controls. Maximum reach uses the whole extended arm — for occasional controls only.

Reach is sized from the smallest user, pulling surfaces lower and nearer; clearance is sized from the largest user, pushing them higher and wider. No single fixed geometry satisfies both, so the workstation adjusts.

Inside normal reach, however rarely it is used. Frequency sets the zone for ordinary controls, but a safety-critical control must be reachable instantly without stretching.

The study of the systems and biomechanics within the human body — their responses, limitations and capabilities. It tells a designer what a user can DO, where anthropometrics tells them how big the user is.

Visual accuracy, colour perception, strength, fatigue, muscle control and hearing thresholds.

Roughly 1 in 12 men has reduced red–green discrimination, so a colour-only code carries no information for them. Add a second channel — shape, position, a symbol, a pattern or text.

Fatigue lowers what the body can deliver as a task is repeated. A demand that sits just inside the limit for a rested user is outside it later in the shift.

The study of the human mind, including all the senses that send information to the brain — sight, sound, touch, smell and taste — and how they influence the design and development of products.

Smell: an odorant added to naturally odourless natural gas so leaks are detected. Taste: a bittering agent in detergent capsules so a child spits one out.

Carrying critical information through more than one sense — an alarm that both sounds and flashes. A single channel fails completely for part of the user group, while two degrade gracefully.

A flat screen gives no tactile detent, so the user has no confirmation that a press registered. Sound and haptics replace the feedback a physical button would have given by touch.

Waste, pollution and energy consumption — and all three are affected more by how long the product lasts than by what it is made of.

Doubling the time a product stays in use halves its material, energy and waste at once, because one product does the work of two. No material substitution comes close.

For anything powered the use phase dominates, so insulation and control matter. For anything passive the embodied impact dominates, so mass, processes and life matter.

A measure, a cost and an alternative — for example, "the recycled grade costs 12% more per part and removes the coating, recovered within a year".

Cyclic (creates no waste), solar (uses clean energy), safe (causes no harm), efficient (least material and energy), social (supports basic human rights).

That every part can return to a cycle — made from recycled or renewable material and recyclable or compostable at the end. A laminate or a glued joint usually breaks it.

Mass and energy only mean something against the service delivered. A chair 40% lighter that lasts half as long uses more material per year of use.

Below tier one of the supply chain: final assembly is visible and audited, while the fabric, fixings and raw materials are two or three tiers away and rarely traced.

Measuring a product against three accounts — people (social), profit (economic) and planet (environmental) — together rather than measuring profit alone.

Users, the community round the factory, everyone in the supply chain, and the people who repair, clean or dispose of the product. The supply chain is the forgotten part.

A design that loses money is never manufactured, so it helps nobody. Profit is a constraint to be met, not a villain, and the version that ships balances all three.

By changing what the product IS rather than optimising what it was: shipping concentrate instead of water, renting a tool instead of selling one.

Find the account that is quietly paying and name what it pays for. A product that seems unusually cheap or convenient is being subsidised by people, profit or planet.

A decision that moves a cost instead of removing it — a thinner bottle onto the user, a refill onto the household, automation from profit onto people. Check all three accounts after any change.

Safety and legality are not tradeable. Then favour the account that cannot recover — a lost livelihood or habitat — over one that can. Then take the whole-life view of profit.

Durability that costs more per unit is usually cheaper per year of service, so what looks like profit against planet at the till is often profit and planet over ten years.

Linear runs take, make, use, dispose — value created once and destroyed once. Circular is a closed loop where disposal becomes a return and resources are continuously repurposed.

Maintain keeps everything; reuse nearly everything; repair keeps the assembly; remanufacture keeps the parts; recycling keeps only the material.

It was designed to be thrown away and then partly rescued. Circular means the return was designed in — bolted not glued, separable materials, and a business that wants it back.

The embodied energy of forming and assembling a product is usually far larger than the energy in its raw material, so keeping the artefact is worth more than keeping the substance.

Longevity, upgradability, disassembly and dematerialization — with longevity first, because doubling the time in use halves everything else.

"Separated into material streams in under five minutes with standard tools", tested with a prototype, a screwdriver and a timer, by somebody who has not seen it before.

One unobtainable part. A product engineered for ten years with a five-year spares policy is a five-year product.

Extraction and processing waste ore, water and energy far exceeding the mass of the finished part, and manufacture adds offcuts, sprues and rejects.

A technical cycle, where metals and polymers are recovered and remade, and a biological cycle, where materials return safely to natural systems.

Where a product is used once, contaminated in use, lost during use, or too small to sort — situations where collection for the technical cycle cannot happen.

Degradable only breaks into smaller pieces. Biodegradable is converted by micro-organisms to water, carbon dioxide and biomass. Compostable is biodegradable within a defined time with no toxic residue.

A durable product should last; decomposition undermines the property that makes it sustainable. One recyclable polymer with a twenty-year life beats it on every account.

Reuse keeps everything; repair keeps the assembly; remanufacture keeps the parts; recycling keeps only the material. Take-back legislation keeps nothing itself but opens the route.

Standard fixings rather than glue or welds, a documented procedure, and spares available for the whole product life. A short spares policy cancels the design work.

It can require collection but cannot open a glued box or separate a bonded laminate. Every route depends on a design decision taken years earlier.

Rental and leasing, deposits and trade-ins, selling an outcome rather than an object, and producer responsibility — all of which make the return profitable rather than a cost.

Solar, wind, hydro and tidal, biomass and biofuel, and geothermal — each with a limit, which is why a real grid uses several.

Every loop involves collection, transport, sorting, cleaning, remanufacture and redistribution, none of which is free — and for a low-value material it can cost more than the material is worth.

The same material is moved and processed many times. If each movement burns fuel, the total emissions can exceed those of a single new item.

You cannot run a closed material loop on an open energy loop. If the energy is consumed and gone, the system is only half circular.

Examine how the product performs; determine its strengths and weaknesses; turn the weaknesses into opportunities for improvement.

An analysis ties every observation to a consequence, so it changes what you would design next. A description only says what the product is like.

So the redesign can be shown to have improved it. "Tips at 4 kg placed 80 mm in" can be re-measured; "a bit unstable" cannot.

State it with a measurement, say what it costs the user, name the feature responsible, and write it as a testable requirement ready for a specification.

Users: what happens at the task. Manufacturers: what is expensive and where rejects come from. Engineers: what the design is limited by. Service: what breaks and what they refuse to fix. Retail: why it is bought or returned.

People give reasons and priorities but misreport their own behaviour; testing gives numbers against a stated condition but only for what you thought to measure. The strongest findings are where the two agree.

It is existing user research in quantity, written by people at the moment they decided the product had failed them — and it is already in the client's records.

They have adapted to the faults and report the product as acceptable, and the people who gave up — who hold the strongest finding — are absent.

Strengths and weaknesses are internal to the product and true now. Opportunities and threats are external and about what is coming.

Function, performance, usability, features and materials — tagging each entry with its lens stops the SWOT collapsing into four opinions.

It is the weakness written again. An opportunity is external — a market gap, a regulation, a supplier or a rival's absence — that the product could exploit.

Strength with opportunity gives what to push. Weakness with threat gives what to fix first. Those two pairs are the output, not the four lists.

Use it first; test it whole; dismantle in order; analyse the parts; infer the decisions. Each ends in recorded data rather than a photograph.

The usability baseline — how long a first-time user takes, where they stop, what they try — can only be measured on a working product, and it is gone once it is in pieces.

Minutes to open, the number and type of tools needed, and how many parts were destroyed getting in — comparable numbers that can be set against a rival or a redesign.

It is usually there for a reason you have not thought of — a standard, a patent route, a manufacturing constraint, an old failure. Removing it blindly reintroduces a solved problem.

Everybody good = a saturated row, nothing to win. One rival ahead = a gap to close. You ahead = a strength to protect. Everybody weak = the unmet need, and the real opportunity.

A column tells you which existing product is best, and copying it produces a fifth version of what exists. A row nobody has answered gives you something rivals cannot match by tuning.

Otherwise you compare test conditions rather than products. Figures from four manufacturers' websites compare four marketing departments.

A market usually converges on one answer, so every competitor shares the same blind spot. A watering can and a fuel can both pour one-handed and neither competes with a kettle.

The deliberate habit of refusing to accept that something which works is as good as it can be — and converting the irritation into a stated need somebody could design against.

What everybody accepts; what you notice anyway, with a measurement; the question you refuse to stop asking; and the finding stated as an unmet need.

Wheels and suitcases both existed for decades before anyone combined them. Nobody lacked the technology — everybody had accepted that a suitcase is a thing you carry.

"Needs a lighter kettle" chooses the answer before ideation. "Needs to fill and pour without lifting it" leaves several very different products possible.

Empathizing (where does the current product fail?), defining (what baseline must be beaten?), ideation (how do others solve this?), and evaluating (did the new design beat the old?).

A before-and-after comparison on the same measurements — so the final evaluation can show improvement rather than claim it.

It tells you what a redesign would have to give up as well as gain. The part you cannot explain is usually there for a standard, a patent or an old failure.

Competitors share the market's assumptions, including the wrong ones. The principle that solves your problem has usually been found somewhere it was not called the same thing.

Their needs (what the product must achieve), their wants (what they would prefer) and their limitations (what they cannot do).

By understanding users' needs and by carrying out their tasks in the specified environment — doing the task where it is really done, not imagining it from a desk.

Products that meet a need but ignore a want get abandoned. A medication reminder that works perfectly but looks medical ends up in a drawer.

A design process that pays particular attention to the needs of potential users of a product through the involvement of users at ALL stages of the design process.

Specify the context of use; specify the requirements; produce design solutions; evaluate against the requirements; iterate.

The product fits a diverse range of user needs and capabilities, and expensive mistakes are found while they are still cheap to fix rather than after tooling.

It takes longer and costs more up front, and a poor user sample lets a vocal minority pull the design away from the wider population.

The user, the task and the environment.

Because no single discipline covers the user, the task and the environment. Each specialist notices a kind of failure the others are not equipped to see.

An understanding of how users perceive information, make decisions and make errors — especially under stress or time pressure. It informs the USER side.

An understanding of how the setting, the culture and the daily routine shape the way a product is actually used. It informs the ENVIRONMENT side.

Field research, task analysis, user observation, interviews, surveys and focus groups.

Watching methods (field research, observation, task analysis) show what users DO. Asking methods (interviews, focus groups, surveys) report what users SAY. The gap between them is where design opportunities hide.

When you need to measure how COMMON something is across a population — after a deeper method has told you what to ask about.

One confident participant can pull the whole room, so the result reflects the loudest voice rather than the user population.

One named user built from research data who represents the attributes of a user population — with goals, context and constraints specific enough to force a design decision.

A written account of the persona performing a task in a specific situation. It surfaces constraints a persona alone does not — the time of day, the lighting, whether a hand is free.

An expectation a whole population shares about how something behaves: red means stop, clockwise means more. Designing against one causes errors under pressure, however logical the alternative.

Advantage: the team shares one concrete user instead of arguing about an abstraction. Disadvantage: a persona built on thin data gives the designer's assumptions false authority.

How closely the prototype resembles the finished product — in appearance, in materials, and in whether it actually works.

It is fast and cheap, so many ideas can be tested; and users criticise a rough model honestly, because it is obviously unfinished.

It is slow and expensive, so few can be made; and the team and users become reluctant to change something that already looks finished.

They explore ideas, refine them, and communicate them. Each job suits a different kind of drawing.

Informal (freehand sketch): fast and disposable, so many ideas can be explored. Formal (isometric, orthographic, exploded): unambiguous and to scale, so it can be manufactured from.

All three axes are drawn at 30° to the horizontal, and nothing gets smaller with distance — so measurements stay true along each axis.

Showing how a product assembles: the parts are separated along the axes they assemble on, in order, so sequence and every component are visible at once.

To answer a question about the design before the product is committed to — testing an idea, gathering user feedback, communicating the design, and finding problems while they are cheap to fix.

By the question. Anything the body judges (weight, grip, texture, fatigue) needs a physical prototype. Comparing many variants, or examining forces inside a part, suits a virtual one.

Comfort is a felt response to pressure, texture, temperature and time. A model can give mass and geometry, but none of those is an output of the simulation.

Scale, aesthetics, materials, function and performance.

As the mechanism alone in a rough open frame. It is quick to build, and testers comment on whether it works rather than on how it looks.

So the comparison is fair. If the shapes differ, any difference in feel, stiffness or finish could come from the shape rather than the material.

What happens over time — wear, heat, fatigue and the failures that only appear after thousands of cycles.

A surface model defines the outer skin only, used for complex curved styling. A solid model defines the whole volume, so it has mass, a centre of gravity and material properties, and can be analysed or manufactured.

The designer supplies constraints — loads, fixings, material, allowed space — and the software produces geometries that meet them, often shapes a designer would not have drawn.

Divides a part into many small elements and predicts stress, deflection and where it will fail under a stated load, before anything is manufactured.

All three simulate USE rather than form or strength: reach and clearance, being inside the design at full size, and force feedback on a virtual control.

Creating physical prototypes quickly, straight from a CAD model, so potential users and design teams can interact with them and give feedback that drives development forward.

A laser cures liquid photopolymer resin layer by layer. It gives the finest detail and smoothest surface of the three, so it suits appearance models. Parts are brittle and need supports.

A heated nozzle melts thermoplastic filament and draws each layer. It is by far the cheapest and most available, but has visible layer lines and is weaker across the layers than along them.

The part is built inside a bed of loose polymer powder that the laser fuses selectively. Overhangs rest on powder already present, so nothing has to be printed to support them.

By their physical, chemical and mechanical properties.

Measure it and put it back. If the material is unchanged the property is physical; if it reacted and was altered, it is chemical.

It lets a designer eliminate candidates systematically, and it lets unlike materials be compared on the same measured terms using published data rather than testing everything.

As natural (timbers, textiles, biomaterials) or human-made (metals, polymers, glass, composites, smart materials).

One that carries its loads through a skeleton of linear members, with the spaces between open or non-structural. A bicycle, a roof truss, a tent.

One where the outer skin itself carries the load, usually because it is curved. It encloses and protects while using very little material for the volume it contains.

Because real products use each structure where its advantage matters — a car has a frame chassis, shell body panels and solid brake discs.

Because the requirements conflict — light fights heat-resistant, warm-looking fights damp-proof — so no candidate satisfies every one and the designer must decide which matter most.

Physical, chemical and mechanical properties, plus aesthetic characteristics. The first three are measured; aesthetics are judged against the brief.

Safety requirements — food contact, flammability, electrical insulation — anything that would make the product fail in use, and anything a standard requires.

One that can be measured or observed without the material changing in any way.

Density, thermal expansion, thermal conductivity, melting point, electrical resistivity and electrical conductivity.

Mass per unit volume, in kg/m³ or g/cm³. It decides how heavy a product is for its size.

Bridges need expansion joints; a metal lid on a glass jar loosens under hot water; two bonded materials with different expansion rates warp or crack.

An aspect of a material that leads to it chemically reacting with another substance — so the material is altered by the encounter.

Corrosion resistance, reactivity (food safe), hygroscopy and flammability.

Its chromium reacts with oxygen to form a thin, self-repairing oxide film. Scratch it and the film reforms, so corrosion cannot get started.

The material absorbs moisture from the air. Timber swells and warps, nylon softens and cardboard loses strength — which is why some polymers must be dried before moulding.

An aspect of a material affected by the application of a force.

Strength is the force needed to break it; stiffness is how much it bends before then. A diving board is strong and deliberately not stiff.

Hardness resists scratching and wear at the surface; toughness is the energy absorbed before fracture. Glass is very hard and not at all tough.

Malleability is being hammered or rolled into SHEET; ductility is being drawn out into WIRE.

Elastic deformation returns to the original shape when the load is removed; plastic deformation stays. A bent paperclip has deformed plastically.

Two or more materials combined to enhance their properties — a matrix that gives shape and a reinforcement that carries the load.

The matrix gives shape, surface and protection, and transfers load into the fibres so they cannot buckle. The reinforcement carries the load and stops the matrix cracking.

GRP: glass fibre in polyester resin. Carbon fibre: carbon fibre in epoxy. Plywood: cross-bonded veneers in adhesive. Reinforced concrete: steel bars in concrete.

They cost more and are labour-intensive to lay up, they fail suddenly rather than bending first, and they are very hard to recycle because the constituents cannot be separated.

A material with one or more properties that can be significantly changed in response to changes in its environment.

Piezoelectricity, shape memory, photochromicity, magneto-rheostatic, electro-rheostatic and thermoelectricity.

A squeeze or vibration produces a voltage — and it runs backwards too: apply a voltage and the material moves. Used in gas-lighter sparks and ultrasound probes.

Because it replaces a mechanism. The material is both sensor and actuator, so there are fewer parts, no wiring and much less to wear out.

One that breaks down in the environment after disposal, or at the end of its useful life, into substances that rejoin natural cycles — water, carbon dioxide and biomass.

Heat, moisture and oxygen. Those exist in an industrial composter and not in a sealed landfill or the sea, so the label alone guarantees nothing.

They close the biological loop: grow the feedstock, make the product, use it, compost it — and its nutrients grow the next crop. Waste is designed out rather than managed.

For a durable product that will be collected and recycled properly. Biomaterials win where collection is unrealistic — packaging, single-use items, things used outdoors.

Research question → method → data you will collect → the design decision the data will settle.

A user group you could go and find this week, and a task those users carry out with a beginning and an end.

Every method has a blind spot. A watching method (observation, field research) shows what happens but not why; an asking method (interview, focus group) gives reasons but people misreport what they did.

Would a different answer change the design? If nothing changes whichever way the data falls, the question is decoration and the hours are better spent elsewhere.

Field research, user observation, interviews, questionnaires and focus groups.

The measurable facts that define a target population — age, gender, income, education, occupation, location, household type and relevant abilities. They define who is in the group; they never say what an individual wants.

It shows exactly what happens and never why. People also behave differently when they know they are watched.

Raw records → a repeated theme → a statement about the user → the want or need. Only the last belongs in a specification.

One specific, named, fictional person built entirely from real user research, standing in for a whole group of users so that design decisions are argued about a person rather than a category.

Who (name, age, situation), behaviour, environment, goal and frustration — each traced back to a research finding.

The design must satisfy it above all others: if the product works for nobody else, it must still work for the primary persona.

One person cannot represent the range of a real population, so needs at the edges get designed out — and an invented persona is worse than none, because the invention gets designed for.

Learnability, efficiency, memorability, errors and satisfaction.

Learnability is the first use — can a newcomer finish unaided? Memorability is a return after weeks — can they still do it without relearning?

How many errors are made, how serious each one is, and how easily it can be recovered from.

A measurement taken the same way before and after: for example 6 of 20 first-time users completing the task unaided, rather than "it is hard to learn".

A breakdown of a user's goal into the steps and sub-steps they actually perform, built from observation, used to find where the task goes wrong.

A goal written as the product's function assumes the solution. "Get the child safely strapped in" leaves every design open; "operate the harness" does not.

A step where errors happen, where the task takes far longer than it should, or where users abandon it. Each one becomes a specific design improvement.

You add sub-steps only where users hesitate, struggle or make mistakes. Breaking every step to the same depth produces a big diagram that points at nothing.

Empathize; define the project; ideation and modelling; designing a solution; presenting a solution.

Research findings from real users, a primary persona, and a user journey with pain points marked.

A problem statement, and a design specification whose criteria are testable and split into essential and desirable.

Because testing and users keep producing information that invalidates an earlier decision. A failed test sends you back to ideation; a missing requirement sends you back to the specification.

Diverge — generate many genuinely different approaches with judgement suspended — then converge, narrowing against the specification. They must never happen at the same time.

Brainstorming, mind mapping, thumbnail sketching, morphological analysis, and analogy or biomimicry.

They solve the problem by a different principle, so they fail and succeed for different reasons. If two ideas fail for the same reason, they are one idea.

Far enough to be judged and no further — card, foam or a quick CAD massing — all at the same fidelity, and modelling whatever part would kill the idea if it did not work.

The design specification and user needs — never personal preference. Criteria in the rows, ideas in the columns, every cell scored.

Score every cell, remove anything that fails an essential criterion, then use the desirables to choose between the survivors, and finally check the survivor against the persona.

Because several small desirables can then outvote a single essential — the exact decision the essential-desirable split exists to prevent.

An improved idea rather than a winner: the comparison shows which part of each idea was doing the work, and the developed design takes the best parts of several.

Model — build the cheapest thing that answers the current question. Test — with real users, measuring something. Refine — change the design because of what happened. Then repeat.

Because the questions get harder. Reach can be answered with card at the right height; stability needs real weight and real materials.

So an improvement can be attributed to a known change. Two changes at once hide which one worked, and can hide one making things worse.

When every essential criterion has been measured and met — not at the deadline and not when the model looks finished. Criteria not yet met are recorded honestly.

To generate performance data when tested with end-users — not to show what the product will look like.

From the question being asked. Card at the right height answers reach; a real pivot answers grip; real materials answer stability and mass.

Decide the measurement before the users arrive, give a task rather than an opinion prompt, do not help or explain, and record exactly the quantity the specification criterion names.

Because a printed part is weak across its layers and a card model has no weight. An evaluation that claims more than the model could show is worth less than one that names its limits.

Dimensioned orthographic views of every part, dimensions from a datum, a stated scale, detail views of joints at a larger scale, and an exploded assembly with numbered parts and a parts list.

Chained dimensions accumulate error along the chain; from a single datum each error stays independent.

Could somebody who has never seen the prototype build it from these sheets alone, without asking a question? Anything missing becomes a decision somebody else makes for you.

It carries appearance and proportion but no dimensions, scale, sections, materials or parts list — nothing can be cut or ordered from it. Its job is presenting the solution.

Why does this need to exist, what does it do, and how do you know it works — in that order.

It makes a point faster than a sentence could: the feature shown in use, a ghosted view of something hidden, or a section proving a claim such as cleanability.

Because measuring the miss and naming the next step reads as control of the project, while dropping the line reads as not having tested — and the gap is easy to see.

On the design intention, in the words of the problem statement — the stated need, now met — and, for a specific audience, what it changes for them.

Primary is first-hand data you collected for this project. Secondary is data collected and published by a third party for their own purposes.

Qualitative describes — reasons, feelings, behaviour, the users' own words. Quantitative counts — times, frequencies, dimensions, percentages.

Your own timings, tallies or measurements: for example how many seconds a nurse spends repositioning a table, recorded across twenty meals.

It is fast and free, it sets the standards and numbers you cannot measure, and it stops you spending limited primary hours on a question that is already answered.

User observations, interviews, surveys, questionnaires, focus groups, material testing and product analysis.

User requirements, design specification criteria, the persona, and suggestions for further development of a solution.

A stated condition rather than a vague quality — 200 wipes with a named disinfectant, not "is it durable" — plus identical samples, the same procedure each time, and a control.

Opinions tend to support whatever the designer already planned. A behaviour question produces a count that can contradict you, which is the only kind worth the hours.

Internet-based research, government data and statistics, university research, and a literature search.

To support or validate primary research: it supplies population data and standards you cannot measure, and it shows whether your own finding is normal or unusual.

Who wrote it and what do they gain? When was it produced? Where did their numbers come from, and from how many people? Who checked it before publication?

Nobody can check who produced it or how, so the figure cannot be defended. Citing also exposes the case where several of your sources are repeating one original.

Findings about users' experience, motivations and interactions — written up as a persona for each user group, plus a journey with pain points.

It is a problem the user found serious enough to solve themselves, so it shows both the problem and the kind of solution that is acceptable to them.

Name the groups, choose a primary and say why, then accommodate the others where it costs the primary nothing — resolving the conflict with a feature rather than averaging it.

They explain behaviour that otherwise looks irrational. A patient unwilling to be a nuisance will not press a call button, which rules out solutions that depend on asking for help.

The whole experience of carrying out a task, drawn as a storyboard of frames in order — starting before the user touches the product and ending after they leave it.

Marking how the task is going at each frame, so the troughs become visible. A trough you can point at is much harder to argue with than a sentence.

A frame where the journey goes wrong — the user hesitates, does extra work, feels unsafe or gives up. Each one must be stated as an observed action and effect.

A design opportunity: something specific enough to sketch and then test. A storyboard with troughs and no opportunities has diagnosed a problem and left it there.

Function — what it is for and what each part contributes. Performance — how well it does it, in numbers. Features — what it has, who each one serves, and which are never used.

It is the only one that produces baseline numbers. Without them, "better than the existing product" cannot be claimed or tested.

Either it is not needed — so it can go, freeing cost and weight — or it is not understood, which is a usability failure. Both are findings.

State the problem abstractly, find any product that solves it, and borrow the principle rather than the shape — then name the constraint that stops you copying it outright.

WHO has the problem (a recruitable group), what they NEED A WAY TO do (an outcome, never a product), and BECAUSE — the research insight with its evidence.

Because every idea generated afterwards becomes a variation of that one solution, so ideation has been decided before any analysis happened.

Could someone else recruit your users from it? Does it name an outcome rather than a product? Is the BECAUSE something you found out? Would three very different ideas all satisfy it?

It is what the final evaluation is judged against — whether the stated need is now met. A statement too vague to answer that was never specific enough.

A finding behind it, a statement of what the solution must DO, a number or condition, a test, and a band — essential or desirable.

Essential: the solution fails without it, so it filters ideas out. Desirable: a real improvement taken if it costs nothing else, used to break ties between ideas that all pass.

"Made from aluminium" writes a solution into the specification and rules out better ones. The criterion is the behaviour aluminium was wanted for.

To compare ideas against each other, to decide when development is finished, and to structure the final evaluation — which is why a vague one costs marks three stages later.

Isometric shows the whole object in three dimensions to communicate a concept. Orthographic gives front, plan and side in true size so a manufacturer can work to the dimensions.

Dashed is a hidden edge — real, but not visible from that direction. Chain-dotted is a centre line, marking the axis of a hole or cylinder.

Third angle places each view on the side you looked from; first angle places it on the opposite side. The symbol on the sheet says which, because reading it wrongly produces a mirror-image part.

When the question is about the ORDER of assembly — which part goes on first and which fixing goes where. An assembly drawing shows the fitted result but not the sequence.

Anything the body judges: weight, reach, grip, balance, fatigue, and fit in a real space with real obstructions.

Scale — full size wherever a body is involved. Shape — the form in the hand, weighted to the real mass. Space — whether it fits in the real place it must be used.

An aesthetic prototype tests how it looks and feels and need not work. A functional prototype tests whether it does the job and may look like nothing. One prototype doing both usually does neither.

Unweighted, it flatters every design — with no mass there is no wrist torque, so every grip shape feels comfortable and the test cannot tell them apart.

Surface knows only the skin. Solid knows the whole enclosed volume, so it can report mass and sections. Virtual knows geometry plus behaviour — motion, loads and materials.

It has no inside — only a skin with no thickness — so there is nothing for a density to act on.

The model is built from editable dimensions, so changing one updates every dependent feature. A variant costs minutes rather than a rebuild, which is what makes iterating affordable.

It cannot tell you what a product feels like to use — weight, balance, grip, fatigue or fit in a cluttered real space. Those need a weighted physical model.

A material, so stiffness and strength are known; the loads — how much, where and in what direction; and the constraints saying which faces are held still.

No. Red is the highest stress in that simulation. Failure depends on whether the peak exceeds the yield strength of the material, which the numbered scale tells you.

The load has to change direction through a small area. A generous fillet radius lets the stress flow round gradually, which is usually the cheapest fix available.

Anything outside the case described: being dropped, loaded off-centre, corroded, or fatigued over many cycles. It also assumes a perfect material, which a printed part is not.

Watertight solid, wall thickness against the nozzle or beam width, orientation, overhangs and reachable supports, and designed clearances at mating faces.

It fixes which faces print well, which surfaces overhang and need support, and the direction the part is weak in — so every other decision depends on it.

Typically 0.2 to 0.4 mm per mating face. Modelled at the exact nominal size, printed parts come off the bed fused together.

A printed part is not the production part: FDM is far weaker across its layers than a moulded part is in any direction, and SLA embrittles in sunlight.

They answer different questions — users about the body and the task, clients about budget, installation and what the organisation owns — and in one room the client talks while the users agree.

Decide the measurement before the session, give a task rather than an opinion prompt, say nothing and do not help, record behaviour as well as words, and ask the open question only at the end.

Pair it with what was observed, work out what it means about the design, then decide the change — and retest with the same task, users and measurement.

When the behaviour does not support the words: three users calling a tool heavy while nobody slows down is worth recording and watching, not redesigning for.

At the requirement, not the material. Each requirement names a property with a number, which a candidate either meets or does not.

As a filter: a candidate failing one is out however well it scores elsewhere. Mass, cost, availability and aesthetics then rank whatever survives.

Stiffness. Strength is the load before it breaks; stiffness is how little it bends before then. Section depth and shape affect stiffness at least as much as the material does.

The requirement, the property it demands, and the consequence for the user. A material name on its own earns nothing.

Texture, form and colour — each enhanced by a finishing technique after the material has been chosen on its properties.

Grip under a wet hand, hiding fingerprints, or preventing dirt being trapped — and it tells a user where to hold something with no instruction.

Anodising converts the surface of the metal itself so there is no coating to chip. Paint sits on top, and once chipped in a wet environment corrosion starts under its edge.

The colour goes right through, so a scratch shows the same colour beneath instead of a different substrate — the difference between looking worn and looking damaged.

Cost per part rather than per kilogram, including processing, waste and finishing — and over the whole product life, since a coating renewed twice is bought three times.

Available in the section and grade required, within the lead time, at a usable order quantity, and ideally from a second source so one supplier cannot stop production.

A product lasting fifteen years in a slightly worse material beats one lasting four in a better one, because the second is made and transported nearly four times over.

Essentials first — cost never buys back a failed property. Then whole-life cost, then what is genuinely available. Finally, state the trade-off you accepted and why.

The requirement from the specification, the property it demands, the evidence for that property, and the trade-off accepted. Missing the evidence link makes it a preference.

Secondary is published — property tables, standards, corrosion charts, supplier data sheets. Primary is your own testing on this material in this environment.

The supplier gains if you believe it and nobody independent checked it. It is evidence of what the material is offered as; a second source makes it a number you can defend.

Every choice gives something up. An answer listing only advantages reads as advocacy; naming the cost and arguing it was worth paying reads as judgement.

To the client who pays, to the community that lives with the product, and to the environment that supplies and absorbs it. Almost every decision reaches all three.

Because a per-unit improvement can be an overall loss. A bottle using 18% less plastic but replaced twice as often uses more material across a year.

Welding an earcup shut is chosen for cost and thinness, and it decides that any fault scraps the whole product. Most environmental damage is a side effect of a decision about something else.

Four questions asked before a decision is fixed: who else lives with this, for how long, what would change it, and can I say why.

A hazard, a test and a limit — so the same product either passes or does not, and two people can agree about the result.

Design the hazard out; if it must exist, guard or interlock it; warn only when neither is possible. Relying on the user is never a safety measure.

Every clause exists because something went wrong somewhere, usually to somebody. No individual designer could discover all of those hazards alone.

That the product is safe for your users in your context. A standard written for adults says nothing about a nursery, and one tested dry says nothing about wet hands.

Planned, functional, technological, style and social. What separates them is what actually ended the product.

Functional means it genuinely broke and cannot economically be repaired. Planned means the useful life was deliberately limited by a design decision.

Measuring a product against people, profit and planet rather than profit alone. Obsolescence is where the three conflict most sharply.

A long-lived product builds the reputation the next one is sold on, avoids total warranty replacements, and avoids legal exposure as repairability rules spread.

Designing one product that works for as many people as possible regardless of age or ability, without a separate special version — covering physical, sensory and cognitive differences.

"Who does this exclude, and what would let them in?" It produces a specific barrier and a specific design change instead of an opinion.

One channel always excludes somebody: a beep fails deaf users and noisy places, a colour change fails colour-blind users and bright sun. Sound plus sight covers both.

One arm; a broken wrist for six weeks; holding a toddler. All three need one-handed use, and only the first appears in a disability statistic.

The middle value of one measurement across a population: half of people measure less and half more on that dimension. It says nothing about any other dimension.

Nobody is at the 50th percentile in several dimensions at once, and combining a few such requirements leaves a band far narrower than half the population.

Where comfort rather than access is at stake and adjustment is genuinely impossible — a fixed seat pitch, say. Even then, name who is disadvantaged and what alternative exists.

State who the product does not serve and why, bound the exclusion with real data, and provide an alternative where one exists — rather than claiming it suits everybody.

Setting each requirement from the user at the limit rather than the average: reach, force and readability from the least capable user, clearance and capacity from the largest.

Ask whether it lets somebody IN or lets something THROUGH. Access requirements come from the least capable user; space and capacity requirements from the largest.

Nobody is designed out, because the requirement is met across the whole range; and one product serves everybody, so there is no special version to design and stock, and no stigma.

Dropped kerbs, designed for wheelchairs and used by every pram and suitcase; lever door handles, an arthritis solution now standard; subtitles, for deaf viewers and watched by about a third of viewers.