How do you know the best ways to make your advertisements compelling? You could follow “best practice”, although that might mean little more than following the herd—where the herd have never genuinely looked at the evidence. Or you could opt for evidence-based advertising. Most people who look for persuasive strategies in advertising probably rely on nonexperimental studies—that is, analyses of data on a collection of advertisements to determine which variables most closely correlate with success. Experimental studies are at the opposite end of the spectrum, controlling the values of all key causal variables. This may be quite difficult to accomplish in practice. Another source of empirical generalizations (EGs) or principles of effective advertising may be based on quasi-experimental studies. In these studies, the design controls for some (but not all) variables when comparing different advertisements.
According to Armstrong and Patnaik, quasi-experimental data “provide a valid and relatively low-cost approach toward developing empirical generalizations”. The cumulative knowledge developed in advertising can be converted into these EGs or “evidence-based principles”. The authors used data from 240 pairs of print advertisements from five editions of the Which Ad Pulled Best series to analyze 56 of the advertising principles from Armstrong’s forthcoming Persuasive Advertising. This analysis compared advertisements using the principle of interest to matched advertisements that did not use the principle. The results are interesting and useful because many advertisements violate these principles.
The authors note that their quasi-experimental findings always agreed with experimental findings, when the latter were available. Their paper lists the principles in order of their importance, including the necessary conditions for them to hold true. Overall, for the 56 principles tested, their was an average 24 percent relative gain in recall. Among the most powerful principles: Offer verifiable evidence (which improved recall by 212%); communicate a Unique Selling Proposition; make the first paragraph relevant; describe a problem and show how the product solves it; include brand and company names (double-branding); and consider celebrity endorsements for gaining attention.