Even in conversation we often get bored or impatient if the one with whom we are talking tells us too many things we already know. Yet we may have an equally negative response if he provides so little information or background that we don't have enough context to put his message in perspective.
As a writer or presenter, one of the best places to start your assessment, your audience analysis, is by looking first to yourself. Think through the connections between you, your listeners, and your topic. Are they in position to know as much about the topic as you do? If your presentation centers on a new workplace process or demand, listeners will have little or no previous knowledge to aid their understanding. But if, on the other hand, your presentation focuses on a revision of one that already exists, then you have shared experiences that you can call on.
Suppose the purpose of your presentation is to win acceptance for a reporting process new to the department you manage. Your explanation of the process would include basics such as definitions of terms and steps in the process. But if your listeners have been working with a process that has been in place for a while, you can move quickly into its revision.
If you're not quite so familiar with your audience, then you have to look outside yourself. You might even have to do some research. Find out what kind of training your audience has. Take a look through a journal that they are likely to have read. You can also gather information from those who have more familiarity with this audience—the event manager, team leader, or facilitator. Question them about the experience your audience may already have had with your topic.
If you will be speaking to a pharmaceutical group preparing for an FDA Advisory Committee meeting, for example, the team leader will know or can easily find out which members have made such an appearance before. If none or only a few have, you might want to address basics such as room arrangement, speaking order, and the procedural rules that govern such a meeting. But for a group that already has that knowledge, you can skim over the basics and head toward the more complex messages concerning scripts, delivery, visuals, and Q&A.
What you learn from your analysis will lead you in your preparation, helping you choose what background to present, what examples to offer, what knowledge to supply. If you do your assessment well, then, like Goldilocks, listeners will settle into a chair that fits well, knowing that you have gotten it just right.