seizure {cold}

Epileptic Seizure

Description

The dataset has the number of epileptic seizures in each of four two-week intervals, and in a baseline eight-week interval, for treatment and control groups with a total of 59 individuals.

Usage

data(seizure)

Format

A data frame with 236 observations on the following 9 variables.

id

identifies de number of the individual profile. This vector contains observations of 59 individual profiles.

y

a numeric vector with the number of epileptic seizures in the four two-weeks intervals observed.

v4

a numeric vector indicating the fourth visit.

time

a numeric vector that identifies the number of the time points observed.

trt

a numeric vector indicator of treatment, whether the patient is treated with placebo (trt=0) or progabide (trt=1)

.

base

the number of epileptic seizures in a baseline 8-week interval.

age

a numeric vector of subject age.

lbase

recode the variable base by log(base/4).

lage

recode the variable age by log(age).

Source

Thall, P.F., and Vail, S.C. (1990). Some covariance models for longitudinal count data with overdispersion. Biometrics, 46, 657–671.

References

Diggle, P.J., Heagerty, P., Liang, K.Y., and Zeger, S.L. (2002). Analysis of Longitudinal Data. 2nd edition. Oxford University Press.

Examples

#####  data = seizure
str(seizure) 

### independence 
seiz0M <- cold(y ~ lage + lbase + v4 + trt + trt:lbase, data = seizure, 
dependence = "ind")
summary(seiz0M)

### AR1
seiz1M <- cold(y ~ lage + lbase + v4 + trt + trt:lbase, data = seizure, 
dependence = "AR1")
summary(seiz1M)

anova(seiz0M, seiz1M)