Department of Psychology, University of Notre Dame, Notre Dame, IN 46556, USA.
Psychol Methods. 2012 Dec;17(4):567-81. doi: 10.1037/a0029317. Epub 2012 Aug 27.
Intra-individual variability over a short period of time may contain important information about how individuals differ from each other. In this article we begin by discussing diverse indicators for quantifying intra-individual variability and indicate their advantages and disadvantages. Then we propose an alternative method that models inter-individual differences in intra-individual variability by separately considering both the amplitude of fluctuations and temporal dependency in the data. In the proposed model, temporal dependency and amplitude of fluctuations are both included as random effects. Parameter estimation is done with a multiple-step approach using maximum likelihood, or with a recommended 1-step approach using a Bayesian method. The similarities and differences between the proposed method and some existing methods are discussed and investigated using diary study data from older adults. The results from empirical data analysis revealed that temporal dependency and amplitude of fluctuations have different predictability of health outcomes and thus should be modeled and considered separately.
个体内短期内的变异性可能包含有关个体间差异的重要信息。在本文中，我们首先讨论了量化个体内变异性的各种指标，并指出了它们的优缺点。然后，我们提出了一种替代方法，通过分别考虑数据中的波动幅度和时间依赖性来对个体内变异性中的个体间差异进行建模。在提出的模型中，时间依赖性和波动幅度都作为随机效应包含在内。使用最大似然法进行参数估计，或者使用推荐的贝叶斯方法一步法进行参数估计。使用老年人日记研究数据讨论并研究了所提出的方法与一些现有方法之间的相似性和差异。实证数据分析的结果表明，时间依赖性和波动幅度对健康结果具有不同的可预测性，因此应该分别进行建模和考虑。
