expand.data: Function to expand data for regression analysis of interval...

In Epi: Statistical Analysis in Epidemiology

Function to expand data for regression analysis of interval censored data.

Description

This is a utility function.

The original records with first.well, last.well and first.ill are expanded to multiple records; several for each interval where the person is known to be well and one where the person is known to fail. At the same time columns for the covariates needed to estimate rates and the response variable are generated.

Usage

expand.data(fu, formula, breaks, data)

Arguments

fu	A 3-column matrix with first.well, last.well and first.ill in each row.
formula	Model fromula, used to derive the model matrix.
breaks	Defines the intervals in which the baseline rate is assumed constant. All follow-up before the first and after the last break is discarded.
data	Datafrem in which fu and formula is interpreted.

Value

Returns a list with three components

rates.frame	Dataframe of covariates for estimation of the baseline rates — one per interval defined by breaks.
cov.frame	Dataframe for estimation of the covariate effects. A data-framed version of the designmatrix from formula.
y	Response vector.

Author(s)

Martyn Plummer, [e-mail]

References

B Carstensen: Regression models for interval censored survival data: application to HIV infection in Danish homosexual men. Statistics in Medicine, 15(20):2177-2189, 1996.

See Also

Icens fit.mult fit.add

Epi documentation built on Oct. 1, 2024, 5:07 p.m.