The fourth format is "comparison." Here, the spotlight's on the claim that your product is superior to those of your competitors. In this Charles Schwab ad, a man complains that he hates his current stockbroker's hefty commissions. At the end of the spot, Schwab promises a better deal.

To me, the difference between "comparison" and "showing the problem" can get a bit fuzzy sometimes. By definition, a comparison highlights the problems with your competitor. Many ads fall somewhere along a continuum between these two formats. Others are more clearly in one camp or the other. For example, a new product treating a malady you've never even heard of before—like, say, "restless leg syndrome"—is a good candidate for a pure "show the problem" approach. (In some cases, the problem is so new that there aren't yet established competitors to compare yourself with.)