Persuasive Advertising - J. Scott Armstrong [113]
Make the comparisons clear and easy. For example, base comparisons on a single dimension, such as the unit price of the product or in “twice the speed.” This helps customers make quick comparisons. This is less important for high-involvement products where people are often willing to mull over difficult comparisons.
To make it easy for customers, compare the brands on attributes that they typically use to make their selections. For example, Apple often advertises that its computers are easier to use than its competitors’.
The featured brand should dominate in comparative ads. It should generally be presented early and late, and both visually and verbally—with little attention to the competitor’s brand. There should be no doubt which brand is being advertised. Here is an example that violated these prescriptions: Pepsi, in a TV commercial, showed a young boy in a poor country putting coins in a dispenser to purchase two Cokes. He then stands on the two Coke cans so he can reach the button for the Pepsi. Once he has purchased the Pepsi, he walks off leaving the two Cokes. This ad, which had no facts, showed the Coca-Cola cans near both the beginning and end of the ad. They were on the screen for over 40 percent of the time, while Pepsi was shown for less than 20 percent.
Comparative advertising helps customers because it typically provides more useful information than non-comparative advertising.
Evidence on the effects of comparative advertising and when it works
A meta-analysis found 77 empirical studies on comparative advertising from 1975–96. (The References section of this book includes five additional studies, all supportive, listed under Grewal et al. 1997.) In general, comparative advertising increased purchase intentions by 22 percent. Comparative ads had a greater effect on increasing purchase intentions for new and established products than for leading products, based on 55 studies, and it was especially effective in improving the attitude toward new brands (Grewal et al. 1997, table 2).
A study of consumer durable ads from four magazines found that non-comparative ads provided about 1.7 pieces of information versus 2.2 for implied-comparison ads, and 3.6 for strict-comparison ads (Harmon, Razzouk, and Stern 1983). Similar findings were obtained in a study of 949 full-page magazine ads; the non-comparative ads had 1.4 pieces of information on average, versus 2.0 for ads with implied comparisons, and 2.5 for strict-comparison ads (Chou et al. 1987).
Indirect evidence on the importance of easy comparisons was provided by lab experiments in which subjects were asked to predict which of two students would have better grades in college. When a quantitative feature was common to both alternatives, the subjects gave more weight to it. For example, they used grade point averages (GPAs) in their decisions, even when they had stated earlier that GPAs were unimportant (Slovic and MacPhillamy 1974).
The value of using easy (alignable) comparisons was shown in a review of eight prior studies, and on a lab experiment on ads for vacuum cleaners and popcorn. Easy comparisons provided a more memorable and persuasive approach than did difficult comparisons. Recall of the easy comparisons was especially useful when the subjects saw these ads and ads for competitive products. The advice to use easy comparisons conflicts with conventional wisdom, whereby many firms often advertise unique features for their brands (Lee and Lee 2007).
Lab experiments showed that highly involved people can make rational choices even when presented with difficult comparisons