A two-part mixed effects model for cigarette purchase task data

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• 作者：Tingting Zhao ; Xianghua Luo ; Haitao Chu ; Chap T. Le ; Leonard H. Epstein and Janet L. Thomas
• 刊名：Journal of the Experimental Analysis of Behavior
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：106
• 期：3
• 页码：242-253
• 全文大小：523K
• ISSN：1938-3711

文摘

The Cigarette Purchase Task is a behavioral economic assessment tool designed to measure the relative reinforcing efficacy of cigarette smoking across different prices. An exponential demand equation has become a standard model for analyzing purchase task data, but its utility is compromised by its inability to accommodate values of zero consumption. We propose a two-part mixed effects model that keeps the same exponential demand equation for modeling nonzero consumption values, while providing a logistic regression for the binary outcome of zero versus nonzero consumption. Therefore, the proposed model can accommodate zero consumption values and retain the features of the exponential demand equation at the same time. As a byproduct, the logistic regression component of the proposed model provides a new demand index, the “derived breakpoint”, for the price above which a subject is more likely to be abstinent than to be smoking. We apply the proposed model to data collected at baseline from college students (N = 1,217) enrolled in a randomized clinical trial utilizing financial incentives to motivate tobacco cessation. Monte Carlo simulations showed that the proposed model provides better fits than an existing model. We note that the proposed methodology is applicable to other purchase task data, for example, drugs of abuse.