¶ … credibility to the receiver's ability to decode the advertising message in the intended way. A number of studies have examined the role of source credibility in advertising. According to Koekemoer and Bird (2004), source credibility, the believability of the communicator, is determined by two major characteristics, trustworthiness and expertise. Trustworthiness is a function of the amount of confidence a receiver has in the intention of the sender. Expertise, on the other hand, refers to the receiver's perception regarding the source's qualifications, knowledge, and experience to make credible statements. The customer perceives a source as credible when the source understands the customer's expectations, needs and problems, and when the source has the knowledge and experience to present the facts in a believable and accurate manner (Koekemoer & Bird, 2004). Researchers have identified additional factors that underlie a source's credibility, one of which is likeability. This characteristic describes the source's attractiveness. Qualities such as candor,...

The most credible source then would be a person who rates high on all three dimensions (CiteMan.com, 2008).
Additional studies have been conducted to measure source credibility and its importance in creating effective advertisements. Not surprisingly, research has found that increasing source credibility positively impacts business or brands in several ways. Whether the spokesperson is an actual customer, a company employee, a celebrity or a model, credibility is important. (Clow, James, Sisk, & Cole, 2011).

Clow et al. discuss several studies that investigated the impact of source credibility. For example, it has been shown that a credible spokesperson provokes a greater attitude change than a less credible spokesperson, and that consumers are more likely to discount messages from spokespersons that they perceive to have low credibility. Research has also shown that source credibility affects the consumer's attitude toward the ad, toward the brand, and towards…