flexmix (version 2.3-19)

seizure: Epileptic Seizure Data

Description

Data from a clinical trial where the effect of intravenous gamma-globulin on suppression of epileptic seizures is studied. Daily observations for a period of 140 days on one patient are given, where the first 27 days are a baseline period without treatment, the remaining 113 days are the treatment period.

Usage

data("seizure")

Format

A data frame with 140 observations on the following 4 variables.

Seizures

A numeric vector, daily counts of epileptic seizures.

Hours

A numeric vector, hours of daily parental observation.

Treatment

A factor with levels No and Yes.

Day

A numeric vector.

References

B. Gruen and F. Leisch. Bootstrapping finite mixture models. In J. Antoch, editor, Compstat 2004--Proceedings in Computational Statistics, 1115--1122. Physika Verlag, Heidelberg, Germany, 2004. ISBN 3-7908-1554-3.

Examples

data("seizure", package = "flexmix")
plot(Seizures/Hours ~ Day, col = as.integer(Treatment),
     pch = as.integer(Treatment), data = seizure)
abline(v = 27.5, lty = 2, col = "grey")
legend(140, 9, c("Baseline", "Treatment"),
       pch = 1:2, col = 1:2, xjust = 1, yjust = 1)

set.seed(123)

## The model presented in the Wang et al paper: two components for
## "good" and "bad" days, respectively, each a Poisson GLM with hours of
## parental observation as offset

seizMix <- flexmix(Seizures ~ Treatment * log(Day),
                   data = seizure, k = 2,
                   model = FLXMRglm(family = "poisson",
                     offset = log(seizure$Hours)))

summary(seizMix)
summary(refit(seizMix))

matplot(seizure$Day, fitted(seizMix)/seizure$Hours, type = "l",
        add = TRUE, col = 3:4)