When delivering data in a presentation, show the conclusions you’ve drawn, not all the details that led you to those conclusions. Because your slides will be up for only a few seconds, your audience will need to process them quickly. People won’t have time to chew on a lot of complex information, and they’re not likely to run up to the wall for a closer look at the numbers. So, think in broad strokes when you’re putting your charts together: What’s the overall trend you’re highlighting? What’s the most striking comparison you’re making? Those are the sorts of questions to answer with projected data.
If your audience wants to know more about how you arrived at your conclusions, you can send along more details in documents or decks that you e-mail instead of present.