Why subject-matter experts struggle to write user documents

Sometimes, people ask whether someone who writes documentation must be a subject-matter expert (SME).

SMEs know the terms and the concepts of the subject:

SMEs forget the problems that non-experts have.
SMEs make logical connections that non-experts do not understand.
SMEs do not tell readers about the things that the SMEs think are 'obvious'. SMEs forget that the readers do not know the 'obvious'.

Frequently, a technical writer makes the same mistakes and assumptions as non-expert readers. Frequently, a technical writer asks the same 'stupid questions' that non-expert readers ask. Capture these mistakes, assumptions, and questions, and the quality of the documentation will increase.

A research report that was commissioned by the Consumer Affairs Directorate of the DTI says, "A writer who is initially unfamiliar with the product will be in the best position to take into account the needs of a first time user." Jeanette Croft & Freda Harris, Writing safety instructions for consumer products, The Qualitative Consultancy, November 1998. URN 96/768.