A principle for setting priorities. The 80/20 Rule states that users will typically use 20% of the features of a system product or service 80% of the time. Therefore, focus the majority (80%) of your design and development effort on the most important (20% of) features of the system, product or service.
Effectiveness is the degree to which an interface - for a product, system or service - facilitates a user in accomplishing the task for which that interface was created or intended.
The degree of facilitation is judged by the degree to which errors are avoided and tasks are completed, which is in turn measured by a simple error count or rate (i.e. a count over time).
The rate at which an interface - for a product, system or service - enables a user to accurately and successfully complete a given task. Whilst faster response times are usually better than slow, consistent response times for comparable kinds of task are also important.
Entity relation diagram
An entity relation diagram is a type of conceptual (or semantic) data model. An entity relation diagram typically consist of three types of thing:
- Entities - which represent discrete objects, e.g. a computer, a song, a rabbit, a person or an organisation (in language terms, entities are nouns)
- Relationships - which represents relationships between entities, e.g. an owns relationship between a person and a car; a proved relationship between a user experience practitioner and a research finding (in language terms, relationships are verbs)
- Attributes - both entities and relationships can have attributes, e.g. the proved relationship may have a date or contentiousness attribute
Entity relation diagrams do not show single entities or single instances of relation. Instead, they show entity and relationship sets.
- Synonyms and see also - contextual enquiry; ethnographic method; ethnographic research
Ethnography is "scientific anthropology", i.e. the quantitative, objective study of individual people in the context of their own culture. Contextual inquiry is a specific form of ethnography, where the "culture" is the user's workplace environment.
- Synonyms and see also - heuristic evaluation; user testing
The process whereby someone - be it expert usability practitioner or ordinary user - tests a system or product in order to investigate its usability and the quality of the user experience more generally.
- Synonyms and see also - informtion architecture
Another term for information architecture. This term is perhaps intended to connote more of an emphasis upon the user (in comparison to IA) with more of an initial focus on process modelling and the overall user journey.