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Exploratory analysis of longitudinal trials with staggered intervention times.

Research output: Contribution to journalJournal articlepeer-review

<mark>Journal publication date</mark>07/2005
Issue number3
Number of pages7
Pages (from-to)479-485
Publication StatusPublished
<mark>Original language</mark>English


Longitudinal trials involving surgical interventions commonly have subject-specific intervention times, due to constraints on the availability of surgeons and operating theatres. Moreover, the intervention often effects a discontinuous change in the mean response. We propose a nonparametric estimator for the mean response profile of longitudinal data with staggered intervention times and a discontinuity at the times of intervention, as an exploratory tool to assist the formulation of a suitable parametric model. We use an adaptation of the standard generalized additive model algorithm for estimation, with smoothing constants chosen by a cross-validation criterion. We illustrate the method using longitudinal data from a trial to assess the effect of lung resection surgery in the treatment of emphysema patients.

Bibliographic note

RAE_import_type : Journal article RAE_uoa_type : Statistics and Operational Research