Strategies for handling normality assumptions in multi-level modeling: A case study estimating trajectories of Health Utilities Index Mark 3

With longitudinal data, lifetime health status dynamics can be estimated by modeling trajectories. Health status trajectories measured by the Health Utilities Index Mark 3 (HUI3) modeled as a function of age alone and also of age and socio-economic covariates revealed non-normal residuals and variance estimation problems. The possibility of transforming the HUI3 distribution to obtain residuals that approximate a normal distribution was investigated.