User-centred design

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.