Persuasive Advertising - J. Scott Armstrong [105]
A qualitative review, which included approximately one hundred papers, concluded that evidence had a strong effect on attitude change (Reinard 1988). Another review yielded a similar conclusion (Reynolds and Reynolds 2002).
In a lab study on preciseness, subjects were asked how much confidence they would have in three informants who answered the following question about Iceland: “Owing to various price regulation measures, this year’s inflation rate was down to 5 percent. Was it higher last year?” The three responses to choose from were: Olafur said “Yes, it was;” Larus said “Yes, it was about 7 percent;” and Jon said “Yes, it was between 5 and 9 percent.” Olafur gave the most general response and Larus gave the most precise one. In general, the subjects were most confident in Larus, and least confident in Olafur. This defies logic because if Larus is right, so too are Olafur and Jon. On the other hand, Olafur could be right, while Larus and Jon are wrong (if inflation were to be 14 percent, for example). Teigen (1990), who conducted this study, refers to the findings as the “preciseness paradox.”
6.3.2. Offer verifiable evidence
If you make a claim based on facts, you should be able to support the facts. Go beyond providing evidence to show the source of the evidence. People should be able to verify that the evidence is correct. When facts are verifiable, people become more confident even if they do not bother to do any verification.
Verifiable evidence is persuasive when an ad has strong arguments for high-involvement products. In particular, it is important when there is news about the product.
Ads should provide the source of evidence so that those in the target market can check it. Supporting evidence can often be made available on the Internet, thus providing interested customers with a low-cost way to check claims.
In a survey of subscribers to the Harvard Business Review, 96 percent of the respondents agreed that “advertisers should be forced to substantiate their claims” (Greyser and Diamond 1974). That is an old survey, but I doubt that these attitudes are much different today.
Advertising agencies should ask companies to support their claims. This support can help protect sellers as well as advertisers. Remember that competitors or consumers might test the claims if the advertiser fails to do so. For example, on March 28, 2008, the Wall Street Journal reported that two New Zealand high-school students, working on a science project, found that GlaxoSmithKline’s blackcurrant drink, Ribena, contained no detectable vitamin C, contrary to the claim in its advertising. The company admitted to 15 charges of misleading advertising in the ensuing legal case. It was fined and ordered to run corrective advertising.
Interestingly, few advertisers follow this principle. A meta-analysis of 60 published empirical studies on information in advertising found that only 4 percent of ads in all media provided either independent or company research (Abernathy and Franke 1996). Thus, by using verifiable evidence to support claims, an advertiser, by being atypical, can increase believability and attention.
In describing an agency’s work for Subaru of America, Rothenberg (1994, p. 335) told how one copywriter claimed that the Subaru SVA had 63 safety features. When asked about the source of that statistic, he said, “I made it up.”
In one study, 58 companies were asked explain the basis for their claims. For example, Bristol-Myers was asked for details about “a study of hospital patients showed … Excedrin is more effective in the relief of pain than twice as many aspirin,” and Ralston-Purina was asked about its claim that Meat Plus is “so good dogs chose it six to one in a recent test over the leading competitive variety.” Sixteen companies did not respond, and of these that did, none were able to substantiate their claims (Cowan and Nader 1969).
In 1971, the U.S. Federal Trade Commission required advertisers to substantiate claims