Psychometric properties of the Purdue Pharmacist Directive Guidance (PPDG) Scale in a sample of diabetes patients in the Southwestern United States.

Despite the fairly widespread adoption of the 10-item Purdue Pharmacist Directive Guidance Scale (PPDG) over the last decade, only one study has assessed its psychometric properties. The present study examined the validity and reliability of the scale in a sample of 99 diabetic patients in the Southwestern United States. Principal axis factor analysis with Varimax rotation yielded two factors, "Instruction" and "Feedback and Goal Setting," similar to those found when the scale was originally developed. Cronbach's alphas for the total scale and the two factors were 0.95, 0.95, and 0.92, respectively. The scale and the two factors correlated significantly and positively with number of visits by patients to the pharmacist in the past 3 mo. These results provide further evidence for the internal consistency, and construct and criterion-related validities of the scale.