A multilevel model of sudden infant death syndrome in England and Wales.

The relationship between migration and sudden infant death syndrome (SIDS) in England and Wales is analyzed using official data for the period 1979-1983. "In this paper, multilevel modelling is used to examine the variability in SIDS deaths at different geographical scales, namely district, county, and regional levels. Given the population-mixing hypothesis, it is possible that high levels of population mixing in one district will have an effect on the spread of infections in an adjacent district, and the rates for individual districts will not be spatially independent of each other. Factors such as climate varying at regional scale may also be important. A log-linear multilevel model is developed to examine these issues, and the discussion focuses on the methodological issues raised by the analysis such as appropriate multilevel structure, methods of estimation, dispersion of residuals, and significance of parameter estimates."