Measuring organizational sponsorship credibility: The application of source credibility theory in determining the most effective advocacy advertisement sponsor

Background. In marketing and advertising research, spokesperson and corporate source credibility has been studied as a predictor and outcome variable in tangible goods and service advertising. However, no scales have been developed to measure organizational source credibility in advocacy advertising.;Objectives. The research objectives were to develop an organizational sponsorship credibility scale in the context of advocacy advertisements and determine which sponsor (the government, pharmaceutical manufacturers, or pharmacists) is perceived to be the most credible for a prescription medication anti-importation campaign.;Methods. Rasch measurement, the one-parameter item-response theory model, was used to create a difficulty-ordered equal interval organizational sponsorship credibility scale. The 12-item scale was administered to the general Florida population (N=150) via telephone. Respondents were asked to assess the credibility of each of the three potential advertisement sponsors. One-way repeated measures analysis of variance was used to compare the three mean measures of credibility.;Results. When directly queried, the respondents felt the government, represented by the U.S. Food and Drug Administration (FDA), was the most appropriate sponsor for an anti-importation campaign and that the pharmacists were the most credible. Over 80 percent were somewhat or very likely to believe the information in an advertisement sponsored by the FDA or the pharmacists. The mean measure of perceived sponsorship credibility was the highest for the pharmacists, followed by the FDA, and then the pharmaceutical manufacturers. The validity checks supported the empirical findings.;Conclusion. The sponsorship credibility scale captures and quantifies the credibility construct. In addition to benefiting advocacy campaign development by providing a tool to model other sponsorship evaluations, the current research contributes to the communication and marketing disciplines by enhancing credibility construct definition and source credibility theory.