BACKGROUND Precise assessment tools for psychotic experiences in young people may help identify symptoms early and facilitate advances in treatment. In this study we provide an exemplar - with a paranoia scale for youth - for improving measurement precision for psychotic experiences using item response theory (IRT). We evaluate the psychometric properties of the new measure, test for measurement invariance, and assess its potential for computerised adaptive testing (CAT). METHOD The 18-item Bird Checklist of Adolescent Paranoia (B-CAP) was completed by 1102 adolescents including 301 patients with mental health problems and 801 from the general population. After excluding outliers (n = 10), IRT was used to examine item properties, test reliability, and measurement invariance. The properties of an adaptive B-CAP were assessed using a simulation of 10,000 responses. RESULTS All B-CAP items were highly discriminative (a = 1.14-2.77), whereby small shifts in paranoia led to a higher probability of item endorsement. Test reliability was high (a > 0.90) across a wide range of paranoia severity (θ = -0.45-3.36), with the greatest precision at elevated levels. All items were invariant for gender, age, and population groups. The simulated adaptive B-CAP performed with high accuracy and required only 5-6 items at higher levels of paranoia severity. CONCLUSIONS The B-CAP is a reliable assessment tool with excellent psychometric properties to assess both non-clinical and clinical levels of paranoia in young people, with potential as an efficient adaptive test. In future, these approaches could be used to develop a multidimensional CAT to assess the full range of psychotic experiences in youth.

中文翻译：

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青少年偏执狂的评估：青少年偏执狂鸟类检查表的项目和测试属性

背景 年轻人精神病经历的精确评估工具可能有助于早期识别症状并促进治疗进展。在这项研究中，我们提供了一个范例 - 带有青少年偏执量表 - 使用项目反应理论 (IRT) 提高精神病体验的测量精度。我们评估新测量的心理测量特性，测试测量不变性，并评估其计算机自适应测试 (CAT) 的潜力。方法 18 项青少年偏执狂鸟类检查表 (B-CAP) 由 1102 名青少年完成，其中包括 301 名精神健康问题患者和 801 名普通人群。排除异常值（n = 10）后，IRT 用于检查项目属性、测试可靠性和测量不变性。使用 10,000 次响应的模拟评估了自适应 B-CAP 的特性。结果所有 B-CAP 项目都具有高度区分性 (a = 1.14-2.77)，由此偏执的小变化导致项目认可的可能性更高。在广泛的偏执严重程度 (θ = -0.45-3.36) 中，测试可靠性很高 (a > 0.90)，在升高的水平上精度最高。所有项目对于性别、年龄和人群都是不变的。模拟的自适应 B-CAP 以高精度执行，并且在偏执严重程度较高的情况下只需要 5-6 个项目。结论 B-CAP 是一种可靠的评估工具，具有出色的心理测量特性，可用于评估年轻人的非临床和临床偏执水平，具有作为有效适应性测试的潜力。在未来，