Create, maintain, and utilize personas throughout the UX design process| Nielsen Norman Group
Guidelines for usability test tasks: engage participants by writing task scenarios that are realistic, encourage an action, and don't give away how the interface should be used.| Nielsen Norman Group
When based on user research, personas support user-centered design throughout a project’s lifecycle by making characteristics of key user segments more salient.| Nielsen Norman Group
Narrow- and broad-scope personas achieve different goals. Success depends upon knowing the tradeoffs and structuring your personas’ scope based on what you are trying to achieve.| Nielsen Norman Group