Clustered Ordinal Respiratory Disorder

Description

The respdis data frame has 111 rows and 3 columns. The study described in Miller et. al. (1993) is a randomized clinical trial of a new treatment of respiratory disorder. The study was conducted in 111 patients who were randomly assigned to one of two treatments (active, placebo). At each of four visits during the follow-up period, the response status of each patients was classified on an ordinal scale.

Usage

respdis

Format

This data frame contains the following columns:

y1, y2, y3, y4

ordered factor measured at 4 visits for the response with levels, 1 < 2 < 3, 1 = poor, 2 = good, and 3 = excellent

trt

a factor for treatment with levels, 1 = active, 0 = placebo.

References

Miller, M.E., David, C.S., and Landis, R.J. (1993) The analysis of longitudinal polytomous data: Generalized estimating equation and connections with weighted least squares, Biometrics 49: 1033-1048.

Examples

data(respdis)
resp.l <- reshape(respdis, varying = list(c("y1", "y2", "y3", "y4")),
                  v.names = "resp", direction = "long")
resp.l <- resp.l[order(resp.l$id, resp.l$time),]
fit <- ordgee(ordered(resp) ~ trt, id = id, data = resp.l, int.const = FALSE)
summary(fit)

z <- model.matrix( ~ trt - 1, data = respdis)
ind <- rep(1:111, 4*3/2 * 2^2)
zmat <- z[ind,,drop=FALSE]
fit <- ordgee(ordered(resp) ~ trt, id = id, data = resp.l, int.const = FALSE,
              z = zmat, corstr = "exchangeable")
summary(fit)