acc (version 1.2.4)

aeefit: Fits semiparametric regression models for irregularly observed physical activity data

Description

Fits semiparametric regression models for irregularly observed physical activity data.

Usage

aeefit(formula, data, weight, control=list())

Arguments

formula

A formula object as returned by aee.

data

A data frame which includes individuals' ID, observation times, and minutes of physical activity since the last observation time.

weight

A vector of sampling weights, for each individual.By default, no sampling weights are applied.

control

A list of control parameters. See 'Details'.

Details

The control argument is a list athat can supply any of the following components:

• betaInit: Initial value for covariate coefficient, default is 0.

• interval: Initial search interval for solving beta. Default is (-5,5).

• maxIter: Maximum iterations allowed. Default is 150.

• absTol: Absolute tolerance. Default is 1e-6.

• relTol: Relative tolerance. Default is 1e-6.

• a: A tune parameter. Default is .1. In case of gamma fraility, "a" corresponds to the value of both shape and rate parameters.

References

Wang, X. and Yan, J. (2011). Fitting semiparametric regressions for panel count survival data with an R package spef. Computer Methods and Programs in Biomedicine, 104, 278-285.

Wang, X., Ma, S., and Yan, J. (2013). Augmented estimating equations for semiparametric panel count regression with informative observation times and censoring time. Statistica Sinica, 23, 359-381.

Examples

## Not run: 
# data(NHANES)
# # Example of analyzing NHANES data 
# # Example 1: Not adjusted for sampling weights
# nhanesToFit <- NHANES[ which(NHANES$mvpaMinutes!=0), ]
# formula <- aee(ID, Day, mvpaMinutes) ~ Age+raceBi+VO2max+Gender
# fitted1 <- aeefit(formula=formula, data=nhanesToFit) 
# summary(fitted1)
# 
# # Example 2: Adjusted for sampling weights
# data(weight)
# nhanesToFit <- NHANES[ which(NHANES$mvpaMinutes!=0), ]
# nhanesUnique <- nhanesToFit[!duplicated(nhanesToFit$ID),]
# weightUnique <- merge(nhanesUnique, weight, by="ID")
# selProb=(1/weightUnique$weight)
# formula <- aee(ID, Day, mvpaMinutes) ~ Age+raceBi+VO2max+Gender
# fitted2 <- aeefit(formula=formula, data=nhanesToFit, weight = selProb) 
# summary(fitted2)
# ## End(Not run)