1.2  Identifying Your Purpose and Audience

When you communicate, your purpose is not what you want to do; instead, it is what you want your audience to do as a result of reading what you wrote or listening to what you said. Thus, it involves the audience. To communicate effectively (that is, to achieve your purpose), you must adapt to your audience. Therefore, you must know your audience.

Knowing your purpose and audience helps determine your strategy. If your purpose or audience is unclear, clarify it as best you can, possibly by asking others. For a public thesis defense, for example, the audience is usually strongly heterogeneous. It includes your jury, your colleagues, your friends, and perhaps your family. The purpose depends largely on how your institution sees the event. Some institutions feel that you must primarily address the jury, no matter who else is in the room, as it is your only chance to convince them of your worth. Other institutions see the defense as a way to broaden the visibility of your work and will want you to address a larger audience — including the jury.

Audiences vary. They can be small or large. They can be reasonably homogeneous in what they already know or in what they are interested in, or they can be heterogeneous. Some are reasonably well known, as when you address a letter or memo to a specific person; others are less well defined, as when you publish an article in a magazine. Whenever possible, however, distinguish between specialists and nonspecialists, and between primary readers and secondary readers.

Readers and listeners vary in how much they know about the topic you discuss and about your broader scientific field. Specialists will likely want more detail. They can apply detailed information in their own work, or they might need it to be convinced of the validity of your conclusions. Nonspecialists, on the other hand, need more basic information, especially in the introduction. Nonspecialists also require more interpretation, typically with the conclusions. They also need simpler vocabulary (or definitions), as they have not mastered the technical terms of your field.

Specialism is relative. Any audience can be seen as including both more specialized and less specialized members, all the more so when it is ill defined. Even a scientific paper published in a journal, which you can see as a specialized publication, will likely be read by newcomers to the field who are less specialized. Even referees on the program committee of a conference cannot have an equal degree of expertise in all the proposals they must evaluate. In other words, do not assume that a scientific audience is necessarily composed of "people like you." On the contrary, you may well be the most specialized person on the planet in your specific topic. Effective scientific communication, and in particular effective writing, strives not to exclude readers or listeners. A well-written scientific paper makes sense, at least in its broad lines, to anyone with a scientific background.

Readers might also vary in how familiar they are with the context. When you are writing a document (for example, a letter) to a single person or to a small, well-defined group of people, you might be tempted to jump directly to the heart of the matter, assuming context is unnecessary. This person or group of people, who are your primary readers, may indeed know the context. Still, they may not be mindful of it when they read your document. Moreover, your document might end up being read by people you did not identify, such as those who were forwarded your document by a primary reader or perhaps those who will obtain your document in the future. These people, who are your secondary readers, will not know or remember the context. An effective document makes sense to both primary and secondary readers.