Department of Educational Psychology, University of North Texas.
Department of Statistics, Northwestern University.
Psychol Methods. 2017 Dec;22(4):743-759. doi: 10.1037/met0000134. Epub 2017 Apr 13.
Although immediacy is one of the necessary criteria to show strong evidence of a causal relation in single case designs (SCDs), no inferential statistical tool is currently used to demonstrate it. We propose a Bayesian unknown change-point model to investigate and quantify immediacy in SCD analysis. Unlike visual analysis that considers only 3-5 observations in consecutive phases to investigate immediacy, this model considers all data points. Immediacy is indicated when the posterior distribution of the unknown change-point is narrow around the true value of the change-point. This model can accommodate delayed effects. Monte Carlo simulation for a 2-phase design shows that the posterior standard deviations of the change-points decrease with increase in standardized mean difference between phases and decrease in test length. This method is illustrated with real data. (PsycINFO Database Record
虽然即时性是单病例设计（SCD）中显示因果关系强证据的必要标准之一，但目前没有推理统计工具来证明这一点。我们提出了一种贝叶斯未知变点模型，用于研究和量化 SCD 分析中的即时性。与仅考虑连续阶段中的 3-5 个观测值来研究即时性的视觉分析不同，该模型考虑了所有数据点。当未知变点的后验分布在变点的真实值周围变窄时，表明存在即时性。该模型可以容纳延迟效应。对于 2 相设计的蒙特卡罗模拟表明，随着阶段之间标准化均值差的增加和测试长度的减少，变点的后验标准差减小。该方法用真实数据进行了说明。
