Five Audiences and How to Write for Them . . .

Based on early work about audience analysis by Kenneth Houp and Thomas Pearsall.

General

Readers outside of their particular field of specialization.

Content: Topics that relate to their daily lives; ample background, usually in summary form rather than detail; practical information rather than theory; extended definitions; anecdotes and other human interest information.
Organization: Narrative, chronological, least complex to most complex, most interesting to least interesting, general to specific.
Style/Tone: Informal, readable; plain language—few technical terms and no jargon; active voice; analogies; shorter sentences and paragraphs; generally, 3rd to 9th-grade reading level; verbal explanations of data (rather than formulae and equations).
Layout: Lots of white space, color, other eye-catching graphics.
Illustration: Simple charts, maps, bar graphs, photos.

Readers responsible for decisions regarding personnel, production, or profits.

Interested in effects and costs rather than in theory or mechanical applications.
Need quick access to information because of limited decision-making time.
B.A. or B.S., not necessarily in technical or scientific field.
Broad knowledge of the field, but not actively involved in technical work.
Frequently trained in a technical or specialized field.

Content: Simple and concise background information; recommendations, criteria, discussion of alternatives; statistics on costs, personnel, facilities, markets, possible competition; non-essential data and information in an appendix.
Organization: Important information (conclusions and recommendations, summaries) at the beginning.
Style/Tone: Formal but not stuffy; readable; plain language—technical terms and jargon clearly explained; active voice; verbal explanations of data (rather than formulae and equations); shorter sentences and paragraphs than for expert; overall, similar to general audience, but perhaps a little higher level.
Layout: Pie charts, bar graphs, simple line graphs, tables.
Illustration: Headings, white space for easy access

Readers trained in theory, and probably application, in field of specialization.

Content: Both theory and practical applications of theory; detailed background information; statement of objectives, scope, limitations; research methods outlined in sufficient detail for replication; conclusions drawn from data; references to previous experimentation, research, or publications in the field.
Organization: Conclusions and recommendations are at the end—specific to general (or general to specific to general); typical scientific report form.
Style/Tone: Formal, objective; standard terms, abbreviations, formulae may be used; non-standard usage should be identified and explained; active or passive voice; highly technical mathematics, formulae, equations may be used—verbal explanations may accompany them, but they, too, may be highly technical; longer and more complex sentences and longer paragraphs.
Layout: Tables, line graphs, complex charts, photos.
Illustration: Headings, but not as much white space.

Readers trained to build and maintain specialized equipment.

Interested more in "how" equipment works than in theoretical experimentation or explanation.
High school education; perhaps B.S.
Less theoretical training than expert, but possibly more applied experience and/or training.

Content: Only enough theoretical information to give some background and to help with trouble shooting; often general description of equipment, parts, operation principles, maintenance; emphasis on detail, but less than for expert.
Organization: Sequential or chronological.
Style/Tone Active voice; standard terms and abbreviations may be used, although some definitions may be necessary; formulae and equations should be limited; verbal explanations should always accompany them; short sentences and paragraphs.
Layout: Charts, graphs, and photographs are detailed, but not as complex as for expert.
Illustration: Carefully-labeled drawings; lots of headings, white space, numbered steps, color, graphic techniques (boxes, lines).

Readers responsible for actual operation of equipment.

Interested more in "how" equipment works than in theoretical experimentation or explanation.
High school education or less.

Content: Very general background only; emphasis on mechanical operation; detailed operating instructions.
Organization: Sequential or chronological.
Style/Tone: Active voice and imperative mood; all terms should be fully explained; no formulae and equations; short sentences and paragraphs.
Layout: Illustrations, photos, blow-up diagrams.
Illustration: Tables, charts, and graphs should be used only when necessary for operation; graphic techniques (bold, lines, boxes) to set off notes, cautions, and warnings; lots of white space; carefully-labeled drawings; lots of headings, white space, numbered steps, color, graphic techniques (boxes, lines).