PDI-21
Peters et al. Delusions Inventory (PDI-21)
The Peters et al. Delusions Inventory (PDI-21) is a self-report questionnaire designed to measure the prevalence and intensity of delusional beliefs, even in the general population. It includes items assessing ideas of reference, persecutory ideas and bizarre beliefs, and also makes it possible to quantify the conviction, distress and preoccupation associated with each belief.
- Number of questions
- 21 questions
- Estimated duration
- 10 minutes
- Language
- English
- Original name
- Peters et al. Delusions Inventory
- Target audience
- Adults, general population
- Authors
- Emmanuelle Peters, Daniel Slade, Max Birchwood (1999)
Scoring & interpretation
Each question is answered yes/no. For each item answered "yes", the participant then rates on scales from 1 to 5 the intensity of their conviction, distress and preoccupation. This yields a total score (number of "yes" answers) and subscores for conviction, distress and preoccupation.
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This assessment tool will be added to the platform in about 2 months
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The more votes a questionnaire gets, the sooner it becomes available. With 0 votes, it's planned for the week of Dec 8, 2026.