Source Credibility Measures

Author of Tool: 

McCroskey, J. C., & Teven, J. J.

Key references: 

McCroskey, J. C., & Teven, J. J. (1999).Goodwill: A reexamination of the construct and its measurement. Communication Monographs, 66, 90-103.

Primary use / Purpose: 

Assesses source credibility


Measurement of source credibility has been a concern of the Communication discipline for over 40 years. The first multidimensional measure appeared in the Communication literature in 1966 (McCroskey, J .C., Scales for the measurement of ethos, Speech Monographs, 33, 65-72) and provided scales measuring competence and trustworthiness. Many other studies were conducted over the next 30 years. This Source Credibility Measure is the most complete measure and includes scales for three dimensions: competence, trustworthiness, and goodwill/caring. These are measures of constructs which are parallel to those theorized by Aristotle in The Rhetoric.


The alpha reliabilities of these measures usually range between .80 and .94.The development of these measures employed oblique factor analyses which generated correlated dimensions. That is, the three measures represent unique constructs, but those constructs are intercorrelated, as suggested by Aristotle and found in many research studies. Earlier work had used orthogonal factor analyses which forces uncorrelated factors. Thus, the new measures are more consistent with general rhetorical\social influence theories as well as previous findings.



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