Ih. Langford et G. Bentham, A MULTILEVEL MODEL OF SUDDEN-INFANT-DEATH-SYNDROME IN ENGLAND AND WALES, Environment & planning A, 29(4), 1997, pp. 629-640
It has previously been shown that there is a significant association b
etween mortality from sudden infant death syndrome (SIDS) and rates of
long-term migration between local authority districts in England and
Wales. This evidence supports the theory that exposure to infections,
mediated by population mixing, may be an important factor in many case
s of SIDS. In this paper, multilevel modelling is used to examine the
variability in SIDS deaths at different geographical scales, namely di
strict, county, and regional levels. Given the population-mixing hypot
hesis, it is possible that high levels of population mixing in one dis
trict will have an effect on the spread of infections in an adjacent d
istrict, 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 develop
ed to examine these issues, and the discussion focuses on the methodol
ogical issues raised by the analysis such as appropriate multilevel st
ructure, methods of estimation, dispersion of residuals, and significa
nce of parameter estimates.