Department of Economics, University of Oslo, PO Box 1095, Blindern, Oslo 0317, Norway.
J Epidemiol Community Health. 2010 Dec;64(12):1029-35. doi: 10.1136/jech.2008.081034. Epub 2009 Oct 23.
Earlier investigations have shown mortality effects of community socio-economic resources. However, the sex differences have not been clear, and the estimates may well have been biased because of inadequate control for community factors affecting both the socio-economic resources and mortality. The objective of this study was to see whether any effects appeared when time-invariant community characteristics were controlled by including community dummies (fixed effects) and whether there were any differences between women and men.
Discrete-time hazard models for all-cause mortality were estimated for 1981-2002 for all Norwegians aged 60-89, using register data. There were 730 000 deaths among 1.7 million people observed during 19 million person-years. Average education was measured for 433 municipalities for each of the 22 years.
According to the simplest models, a high average education in the municipality is associated with increased mortality. Control for population size (time-averaged) reversed the effects. Inclusion of municipality dummies instead of population size, to control also for additional unobserved time-invariant municipality characteristics, gave very different results: the effects were even stronger for men, while those for women were no longer significant. The results were quite robust to alternative specifications, including the use of a lagged average-education variable.
The study supports the idea that community socio-economic resources may affect mortality and suggests that sex differentials may deserve more attention. It also illustrates the importance of controlling for time-invariant community factors. Unless these can be easily measured, in future investigations one may consider establishing longitudinal data and using a fixed-effects approach such as that used here.
早期的研究表明社区社会经济资源对死亡率有影响。然而，性别差异并不明显，而且由于对同时影响社会经济资源和死亡率的社区因素控制不足，估计可能存在偏差。本研究的目的是观察当通过包含社区哑变量（固定效应）来控制时不变的社区特征时，是否会出现任何影响，以及女性和男性之间是否存在差异。
使用登记数据，对所有年龄在 60-89 岁的挪威人进行了 1981-2002 年全因死亡率的离散时间风险模型估计。在 1900 万人年的观察期间，有 73 万人死亡。22 年来，对 433 个市镇的平均教育水平进行了测量。
根据最简单的模型，市镇的平均教育水平高与死亡率增加有关。控制人口规模（时间平均）则逆转了这些影响。用市镇哑变量代替人口规模来控制额外的未观察到的时不变的市镇特征，得出了非常不同的结果：对男性的影响更强，而对女性的影响则不再显著。这些结果对替代规范非常稳健，包括使用滞后的平均教育变量。
该研究支持社区社会经济资源可能影响死亡率的观点，并表明性别差异可能值得更多关注。它还说明了控制时不变的社区因素的重要性。除非这些因素很容易测量，否则在未来的研究中，人们可能会考虑建立纵向数据并使用固定效应方法，如这里使用的方法。
