National Institute for Health and Care Research

Measure

Bird Checklist of Adolescent Paranoia (B-CAP)

Age range 11 — 17
Completion time 5 Minutes
Respondent Self Report
Problem areas
Unusual Experiences

Overview

The Bird Checklist of Adolescent Paranoia (B-CAP) is an 18-item self-report questionnaire designed to assess the frequency and severity of paranoid thoughts in adolescents. It assesses three related dimensions of paranoia—social harm, conspiracy ideas, and physical threat—which contribute to an overarching paranoia construct. Respondents rate how often they have experienced each thought during the previous two weeks using a six-point response scale. The measure was developed specifically for young people and is suitable for use in both general-population and mental health service settings. The B-CAP was developed to provide a developmentally appropriate measure of paranoia for young people. Item development incorporated clinical expertise, existing measures of paranoia, and consultation with adolescents regarding the content, wording, response format and layout of the questionnaire.

Scoring & Interpretation

Scoring The B-CAP contains 18 items assessing paranoid thoughts experienced during the previous two weeks. Each item is rated: 0 = Never; 1 = Once; 2 = Couple of times; 3 = Few times a week; 4 = Every day; 5 = All the time. There are no reverse-scored items. Responses to all 18 items are summed to produce a total paranoia score ranging from 0–90, with higher scores indicating greater paranoia. Subscale scores can also be calculated: Social harm = items 1–8; Conspiracy = items 9–13; Physical threat = items 14–18. The following descriptive severity ranges have been proposed: 0–22 = Average; 23–39 = Mildly elevated; 40–53 = Moderate; 54–70 = High; 71–90 = Severe These ranges should be interpreted as descriptive severity ranges rather than diagnostic clinical cut-offs. A computerised adaptive version has also been investigated through simulation. At higher levels of paranoia, accurate assessment could potentially be achieved using approximately 5–6 items, although further validation of the adaptive version is required.

Psychometric Properties

Internal Consistency

The original development study reported excellent internal consistency for the total B-CAP score (Cronbach's α = .92). Subsequent Item Response Theory analysis demonstrated excellent reliability across a broad range of paranoia severity. Equivalent alpha values were > .90 across much of the measured paranoia continuum and ≥ .95 across a substantial portion of the elevated range, with maximum test information corresponding to approximately α = .96. Measurement precision was particularly high at elevated levels of paranoia.

Test-Retest Reliability

Not reported

Factor Structure

The original development study supported three related factors: social harm, conspiracy ideas and physical threat. These were explained by a higher-order general paranoia factor. Exploratory factor analysis indicated that the three factors accounted for approximately 51% of variance. Confirmatory factor analysis demonstrated good fit: χ²(132) = 279.9, χ²/df = 2.12, CFI = .96, TLI = .95, RMSEA = .053, SRMR = .045. Subsequent analysis supported treating the 18 items as sufficiently unidimensional for Item Response Theory purposes. A graded response IRT model demonstrated good fit (CFI = .97, TLI = .96, RMSEA = .053, SRMSR = .076).

Validity

The B-CAP has demonstrated good concurrent/convergent validity. Total scores correlated strongly with the paranoia sub scale of the Specific Psychotic Experiences Questionnaire (SPEQ; r = .84, p <.001) and with the Social Mistrust Scale (r = .68, p < .001).
B-CAP scores were also moderately associated with adolescents ratings that they were more fearful of other people than they believed they should be (r = .41, p < .001).

Measurement Invariance

Bird et al. (2020) examined differential item functioning according to age (11–13 versus 14–17 years), gender (girls versus boys), and population (general population versus young people attending mental health services). No significant differential item functioning was identified using the study's primary criteria. This suggests that the B-CAP functions similarly across these groups and that differences in total scores are unlikely to reflect systematic measurement bias.

Access

The B-CAP is available for download and use through the University of Oxford's Oxford Cognitive Approaches to Psychosis resources.


https://www.psy.ox.ac.uk/research/oxford-cognitive-approaches-to-psychosis/resources/assessment-tools/the-bird-checklist-of-adolescent-paranoia-b-cap

Citation

Original Reference

Bird, J. C., Evans, R., Waite, F., Loe, B. S., & Freeman, D. (2019). Adolescent paranoia: Prevalence, structure, and causal mechanisms. Schizophrenia Bulletin, 45(5), 1134–1142.

References

Bird, J. C., Loe, B. S., Kirkham, M., Fergusson, E. C., Shearn, C., Stratford, H., Teale, A.-L., Waite, F., & Freeman, D. (2020). The assessment of paranoia in young people: Item and test properties of the Bird Checklist of Adolescent Paranoia. Schizophrenia Research, 220, 116–122.

Bird, J. C., Fergusson, E. C., Kirkham, M., Shearn, C., Teale, A.-L., Carr, L., Stratford, H., James, A. C., Waite, F., & Freeman, D. (2021). Paranoia in patients attending child and adolescent mental health services.

Schlier, B., Ellett, L., Thompson, E., Gaudiano, B., Krkovic, K., & Kingston, J. L. (2024). Measuring paranoid beliefs in adolescents: A comparison of the Revised-Green et al.'s Paranoid Thoughts Scale (R-GPTS) and the Bird Checklist of Adolescent Paranoia (B-CAP). Research on Child and Adolescent Psychopathology, 52, 1319–1327.

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