brms (version 0.9.1)

epilepsy: Epileptic seizure counts

Description

Breslow and Clayton (1993) analyse data initially provided by Thall and Vail (1990) concerning seizure counts in a randomised trial of anti-convulsant therapy in epilepsy. Covariates are treatment, 8-week baseline seizure counts, and age of the patients in years.

Usage

epilepsy

source

Thall, P. F., & Vail, S. C. (1990). Some covariance models for longitudinal count data with overdispersion. Biometrics, 46(2), 657-671. Breslow, N. E., & Clayton, D. G. (1993). Approximate inference in generalized linear mixed models. Journal of the American Statistical Association, 88(421), 9-25.

Examples

## poisson regression without random effects. 
fit1 <- brm(count ~ log_Age_c + log_Base4_c * Trt_c, 
            data = epilepsy, family = poisson())
summary(fit1) 
plot(fit1)             
    
## poisson regression with random intercepts of patients and visits
## as well as normal priors for fixed effects parameters.    
fit2 <- brm(count ~ log_Age_c + log_Base4_c * Trt_c 
            + (1|patient) + (1|visit), 
            data = epilepsy, family = poisson(), 
            prior = set_prior("normal(0,5)"))
summary(fit2) 
plot(fit2)