Davidian Marie, Tsiatis Anastasios A, Leon Selene
Marie Davidian and Anastasios A. Tsiatis are Professors, Department of Statistics, North Carolina State University, Raleigh, North Carolina 27695-8203, USA (e-mail:
Stat Sci. 2005 Aug;20(3):261-301. doi: 10.1214/088342305000000151.
The pretest-posttest study is commonplace in numerous applications. Typically, subjects are randomized to two treatments, and response is measured at baseline, prior to intervention with the randomized treatment (pretest), and at prespecified follow-up time (posttest). Interest focuses on the effect of treatments on the change between mean baseline and follow-up response. Missing posttest response for some subjects is routine, and disregarding missing cases can lead to invalid inference. Despite the popularity of this design, a consensus on an appropriate analysis when no data are missing, let alone for taking into account missing follow-up, does not exist. Under a semiparametric perspective on the pretest-posttest model, in which limited distributional assumptions on pretest or posttest response are made, we show how the theory of Robins, Rotnitzky and Zhao may be used to characterize a class of consistent treatment effect estimators and to identify the efficient estimator in the class. We then describe how the theoretical results translate into practice. The development not only shows how a unified framework for inference in this setting emerges from the Robins, Rotnitzky and Zhao theory, but also provides a review and demonstration of the key aspects of this theory in a familiar context. The results are also relevant to the problem of comparing two treatment means with adjustment for baseline covariates.
前后测研究在众多应用中很常见。通常，将受试者随机分配到两种治疗组，并在基线时、在随机治疗干预之前（前测）以及在预先指定的随访时间（后测）测量反应。关注点在于治疗对平均基线与随访反应之间变化的影响。一些受试者的后测反应缺失是常有的事，而忽略缺失病例可能导致无效推断。尽管这种设计很流行，但对于无数据缺失时的恰当分析，更不用说考虑随访缺失情况，尚未达成共识。在前测 - 后测模型的半参数视角下，其中对前测或后测反应做出有限的分布假设，我们展示了如何使用罗宾斯、罗特尼茨基和赵的理论来刻画一类一致的治疗效果估计量，并在该类中识别有效估计量。然后我们描述理论结果如何转化为实践。这一进展不仅展示了在这种情况下如何从罗宾斯、罗特尼茨基和赵的理论中产生一个统一的推断框架，还在一个熟悉的背景下对该理论的关键方面进行了回顾和演示。这些结果也与在调整基线协变量的情况下比较两种治疗均值的问题相关。
