epilepticBC {glmmAK} | R Documentation

## Epileptic seizures, Breslow and Clayton transformed

### Description

This data set considers information from a clinical trial of 59 epileptics, reported by Thall and Vail (1990). For each patient, the number of epileptic seizures was recorded during a baseline period of eight weeks. Patients were then randomized to treatment with the anti-epileptic drug progabide, or to placebo in addition to standard chemotherapy. The number of seizures was then recorded in four consecutive two-weeks intervals.

This is a transformed version of the original data (`epileptic`) which allows directly to fit models described in Breslow and Clayton (1993) or in Kleinman and Ibrahim (1998).

There are 4 rows in the dataset for each of 59 patients.

### Usage

    data(epilepticBC)

### Format

A data frame with 236 observations on the following 10 variables.

`id`
  a unique identifier for the subject in the study.
`visit`
  a numeric vector giving the number of the visit, 1,2,3, and 4 for the four two-weeks intervals following the baseline measurement.
`seizure0`
  a numeric vector giving the number of epileptic seizures in the eight-week period prior the randomization.
`age`
  a numeric vector giving the age (in years) at the entry.
`Seizure`
  a numeric vector giving the number of epileptic seizures in a given two-week interval.
`Base`
  a numeric vector giving the transformed `seizure0`. `Base`=log(`seizure0`/4).
`Trt`
  a numeric vector giving the treatment group.
`Base.Trt`
  a numeric vector giving the interaction covariate `Base`*`Trt`.
`Age`
  a numeric vector giving the transformed age. `Age`=log(`age`).
`Visit`
  a numeric vector giving the centered `visit`. `Visit`=(2*`visit`-5)/10.

### Source

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

### References

Breslow, N. E. and Clayton, D. G. (1993). Approximate inference in generalized linear mixed models. Journal of the American Statistical Association, 88, 9–25.

Kleinman, K. P. and Ibrahim, J. G. (1998). A semi-parametric Bayesian approach to generalized linear mixed models. Statistics in Medicine, 17, 2579–2596.

### See Also

`epileptic`

### Examples

    data(epilepticBC)
    ## maybe str(epilepticBC); plot(epilepticBC) ...

[Package glmmAK version 1.3-1 Index]