Prognostic tool to identify adolescents at risk of cigarette smoking initiation
This short questionnaire consists of 12 questions and quantifies the estimated risk of smoking initiation in the upcoming year. It was developed using data from the NDIT study.
Online form
R Code
Weighted cumulative exposures models
WCE implements a flexible method for modeling cumulative effects of time-varying exposures,
weighted according to their relative proximity in time, and represented by time-dependent covariates.
The current implementation estimates the weight function in the Cox proportional hazards model.
The function that assigns weights to doses taken in the past is estimated using cubic regression splines.
Based on Sylvestre et Abrahamowicz (2009)
Available from CRAN
Simulation algorithm for survival data
This version of the permutational algorithm generates a dataset in which event and censoring times are conditional on
a user-specified list of covariates, some or all of which are time-dependent.
Based on Sylvestre et Abrahamowicz (2008)
Available from CRAN
Identification and classification of groups of trajectories
Implements the three-step procedure proposed by Leffondree et al. (2004) to identify clusters of individual longitudinal trajectories.
The procedure involves:
(1) calculating 24 measures describing the features of the trajectories;
(2) using factor analysis to select a subset of the 24 measures and
(3) using cluster analysis to identify clusters of trajectories, and classify each individual trajectory in one of the clusters.
Additional details in Sylvestre et al. (2006)
Available from CRAN