baselineAdjustment: Perform Baseline Adjustment

In LMMstar: Repeated Measurement Models for Discrete Times

Description

Create a new variable based on a time variable and a group variable where groups are constrained to be equal at specific timepoints.

Usage

baselineAdjustment(object, variable, repetition, constrain, new.level = NULL)

Arguments

object	[data.frame] dataset
variable	[character] Column in the dataset to be constrained at specific timepoints.
repetition	[formula] Time and cluster structure, typically ~time|id. See examples below.
constrain	[vector] Levels of the time variable at which the variable is constained.
new.level	[character or numeric] Level used at the constraint. If NULL, then the first level of the variable argument is used.

Value

A vector of length the number of rows of the dataset.

Examples

data(ncgsL, package = "LMMstar")

## baseline adjustment 1
ncgsL$treat <- baselineAdjustment(ncgsL, variable = "group",
                 repetition= ~ visit|id, constrain = 1)
table(treat = ncgsL$treat, visit = ncgsL$visit, group = ncgsL$group)

e1.lmm <- suppressWarnings(lmm(cholest~visit*treat,
             data=ncgsL, repetition= ~ visit|id,
             structure = "CS"))


## baseline adjustment 2
ncgsL$treat2 <- baselineAdjustment(ncgsL, variable = "group", new.level = "none",
                 repetition= ~ visit|id, constrain = 1)
table(treat = ncgsL$treat2, visit = ncgsL$visit, group = ncgsL$group)

e2.lmm <- suppressWarnings(lmm(cholest~visit*treat2,
             data=ncgsL, repetition= ~ visit|id,
             structure = "CS"))

LMMstar documentation built on Nov. 5, 2021, 1:07 a.m.