In addition to these scales, dimensions used in studies that include organizational credibility and Web site credibility are listed.

validating scale measurement credibility-22

In testing construct validity, Carbone (1975) found that ratings of high- and low-credibility sources were significantly different and in the expected direction across all three dimensions.

Source Credibility Scale (Mc Croskey, 1966) In an experiment that involved rating speakers, Mc Croskey (1966) found Hoyt reliability estimates for authoritativeness and character of .93 and .92, respectively.

For example, scholars have distinguished between an "internal" source or the communicator originating the message and an "external" source or the medium transmitting the message.

Internal sources have included, individuals, groups, organizations or institutions, and even labels (e.g., "liberal") (Sundar & Nass, 2001).

The average alpha across all 15 indices was .84 with all values falling within the "good" to "very good" range.

Organizations as sources in health communication could include, for example, organizational communicators such as the Red Cross or the Centers for Disease Control and Prevention (CDC).

Dimensions used in a scale to measure Web site credibility included the items of "trustworthy," "believable," "credible," "qualified," and "expert" (Dutta-Bergman, 2004).

These scales were selected because of their widespread use and because they were tested for reliability and validity.

They used this scale in five environmental health-risk communication case studies to assess source credibility across the three source types of state public health department, local newspaper, and industry involved.

The scale performed well both within and across the three source types, with an alpha of .83 across the five newspaper measurements, .86 across the five industry measurements, and .83 across the five state public health department measurements.

Psychologically, the source of a communication is "what the receiver imagines the source to be" (Sundar & Nass, 2001, p. The introductory definition of source credibility used in this entry supports an individual, psychological perspective of source as whom or what is perceived as the communicator.