An article on the decline of fish in the oceans in the September issue of Smithsonian magazine dramatically illustrates how powerful hard evidence can be. “Seeing Is Believing” looks at historical research by Loren McClenachan that shows the appalling decline of fish populations in Key West, Florida over time—the fish get much smaller and some species disappear. McClenachan used newspaper articles, ship logs, and other records. The most startling evidence: 100 photos of happy day-tripping anglers at the dock with their catches. In the 1950s, man-size goliath grouper dominate the photos. Twenty-five years later, white margate of a few pounds dominate. Today, hauls are mostly small snapper. The pictures tell a dramatic story that wouldn’t have the same impact with hard numbers alone.

It may not be true that everything you need to know you learned in kindergarten, but the old fairy tale Goldilocks and the Three Bears does contain three key (and often violated) rules for well-targeted communications.

Test, Test, Test Like Goldilocks, we’re all striving for “just right” communications: not too complex and not too simple, not too much and not too little. But while most of us only assume (or hope) we’ve gotten it just right, the fussy home invader knew what was just right because she tested.

Real-world testing is ideal. Is your twice-yearly magazine optimal, or would a smaller quarterly publication serve you better? Test by sending one option to half your list and the other to the rest for a year, then tallying responses or donations for each group. (There are subtleties involved in this kind of testing; this is just a broad outline.)

Wonder if you’re communicating too frequently, or too little? Ask. One client worried that they sent too many e-mail bulletins and mailings. Good thing they surveyed their audience, because they found that if anything, they could be communicating more.

Audience testing isn’t practical for everything, of course. When it isn’t—or if you just don’t have the resources for it—you can set up a battery of internal test questions to find well-grounded answers to common dilemmas.

For instance: Is long or short copy better? (The format will guide you: people will read less on a Web page than on a print page.) What do we need to get across? (To convey a clear, high-level message, don’t clutter it with detail. If you need to make a nuanced case, don’t short your credibility by leaving out supporting facts.) What does our audience want to know? (Don’t tell them more than that. And don’t tell them less—vague, hyped copy designed to “pique interest” rarely does.)

‘Just Right’ Depends on Who’s Judging Answers to your internal test questions will always depend on who your audience is. If you’re selling an expensive, advanced-technology product to businesses, for example, you’ll usually have at least two audiences: nontechnical decision makers with budget authority, and technical staff with advisory authority. Don’t think you can communicate with both in the same way: Goldilocks rejected Papa Bear’s hot porridge; he would have snarled at her tepid choice.

Don’t Fall Asleep Often the biggest mistake communications teams make is failing to regularly evaluate their messages and materials. Alas, we can’t afford to relax—what’s just right now may miss the mark as situations change. When you start to think “I could do this in my sleep,” you are asleep. You could be in for a rude awakening if someone decides to measure your communications effectiveness. Or even worse, you’ll slumber on while your audience takes their business elsewhere.

Next up: What The Three Little Pigs has to teach us about clean tech and green building. (Just kidding.)