Persona.

A useful persona contains what influences decisions and leaves out what only adds colour. Useful elements are: the trigger that starts the search, the goal, the concrete task, prior knowledge of the subject, the environment including the device, past obstacles, the decision criteria and a verbatim quote from a real conversation. Invented details about hobbies, car brand and favourite drink are not useful. They create an appearance of closeness but drive no decision: no layout, no text and no order of steps gets better because of them.

The term goes back to Alan Cooper, who popularised it in software development in the late 1990s. There are two kinds. A research-based persona is built from interviews, observations, analyses of enquiries and usage data; every statement can be traced back to a source. A proto-persona is created in a few hours from a team's existing knowledge and deliberately records what is assumed and not yet evidenced. Both are legitimate; it only becomes a problem when an assumption is later quoted as if it were a finding.

A use case: a trade business serves two very different groups. The first is the private homeowner who buys such a service once in her life, knows little of the jargon, is looking for orientation and a price range, and builds trust through references and photos. The second is the buyer at a general contractor who awards twenty jobs a year, thinks in line items and deadlines, and wants to see capacity, references in commercial construction and a contact person within two minutes. These two models lead directly to two entry pages with a different order, not one page with duplicated content.

The criticism of the tool is justified and belongs with it. Personas can reinforce stereotypes when age, gender and origin are described without relevance, and they can legitimise decisions instead of testing them: 'Ms M. wouldn't want that' ends discussions without proving anything. A strict rule has proven to be the antidote: every statement in a persona points to its source, and anything without a source is marked as an assumption. Personas also do not replace testing with real people. How the data basis is created is described in the entry User Research; the result is checked with usability testing; and the models are translated into concrete sequences in the user flow.