Objective: To assess the reliability and validity of the Parental Perceptions Questionnaire (PPQ) for use in the UK and to investigate whether different approaches to the treatment of 'don't know' (DK) responses have any effect on the psychometric properties.
Methods: The parents of 89 children attending for an examination at a dental teaching hospital and a general dental practice completed the Parental-Caregiver Perceptions Questionnaire (PPQ), global oral health and global impact ratings. Clinical data were also collected. Four approaches were taken to the management of DK responses, one approach involved exclusion of DK responses and three approaches involved adjustment of DK responses (item mean, mean items answered and replacement of DK responses with zero).
Results: All four approaches demonstrated acceptable internal consistency and test-retest reliability of the total scale. The mean items answered and replacement approaches had optimal internal consistency of the subscales of the PPQ. Assessments of criterion validity in relation to global oral health rating were similar when the DK responses were adjusted, but the exclusion of DK responses had a detrimental effect. Construct validity of PPQ in relation to global impact rating and clinical data was acceptable only when responses were adjusted.
Conclusion: These data suggest that if DK responses are adjusted, the reliability and validity of this measure are acceptable for use in the UK.