Psychometric Validation of the Italian 8‐Item Green Paranoid Thoughts Scale (GPTS‐8)
Antonio Preti, Carmelo Masala, Donatella Rita PetrettoABSTRACT
Background
Paranoid ideation ranges from mild social‐evaluative concerns to persecutory beliefs. The eight‐item Green Paranoid Thoughts Scale (GPTS‐8) provides a brief assessment of this continuum through reference and persecution items.
Aims
To examine the psychometric properties of the Italian version of the GPTS‐8, including its factorial structure, reliability, and convergent validity, in a non‐clinical university sample.
Methods
243 university students completed the Italian GPTS‐8 and the Prodromal Questionnaire–Brief (PQ‐B). Confirmatory factor analyses compared unidimensional, two‐factor, bifactor, and second‐order models using maximum likelihood estimation with robust standard errors. Reliability was evaluated using Cronbach's α and McDonald's ω, and item‐level contributions to the general factor were examined using bifactor indices (ECV, ωH, IECV).
Results
The bifactor model showed the best fit, supporting a dominant general paranoia factor alongside specific reference and persecution dimensions. Internal consistency was good for the GPTS‐8 total score ( α = 0.78) and acceptable for the subscales (respectively, 0.68 and 0.66). Item‐level diagnostics indicated that several items primarily reflected the general factor, consistent with a hierarchical organization of paranoid ideation. Item response patterns suggested greater sensitivity at moderate to higher levels of the latent trait. Participants scoring above established PQ‐B thresholds showed significantly higher GPTS‐8 scores across dimensions, supporting convergent validity.
Conclusions
The Italian GPTS‐8 showed satisfactory psychometric properties, providing incremental evidence for its structural validity in an Italian‐speaking context. However, given the use of a convenience student sample, findings should be considered preliminary and not directly generalizable to broader or clinical populations.