The persuasive discourse perspective is based upon the Aristotelian theory of rhetoric. As applied to marketing stimuli, the theoretical components of the PDI measure are ethos, pathos, and logos (cf. McGuire 1969). Ethos refers to persuasive appeals that concentrate on the source rather than the message. A logos appeal provides evidence or information about a concept from which a consumer can form beliefs (Feltham 1994, pp. 531-532). Pathos and logos have been viewed by some as different ends of a continuum that considers the message. Feltham suggests that the subscales be used as individual message facets.
Items were generated from a lexicon of philosophical terms, an encyclopedia of philosophy, speech communication literature, and consultation with colleagues. Subjects from the first sample responded to the scale for 16 stimuli (5 movie clips and 11 advertisements).
The items were examined for within-factor item-to-total correlations. These correlation coefficients ranged from .63 to .91. The average coefficient alpha estimates for Ethos, Logos, and Pathos were .89, .86, and .82, respectively.
Reliability and validity
The average item-to-total correlations for the second study were .79, .78, and .74 for the Pathos, Ethos, and Logos subscales. The average reliability estimates were .83, .79, and .89 for Ethos, Logos, and Pathos, respectively.
Administration, Analysis and Reporting
Statswork comprises a team of professional statisticians which can obliged the professional or student researcher in support to fill the survey instrument, gathering the information, organising the analysis and describing the results.
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