Duncan Brian, Rees Daniel I
Department of Economics, University of Colorado, Denver, CO 80217-3364, USA.
Am J Epidemiol. 2005 Sep 1;162(5):461-70. doi: 10.1093/aje/kwi219. Epub 2005 Aug 2.
Using 1995-1996 data from the first two waves of the National Longitudinal Adolescent Health Study, the authors found that respondents who smoked cigarettes scored, on average, three points higher than did nonsmokers on the Center for Epidemiologic Studies Depression (CES-D) Scale. This gap persists even after accounting for observable factors, such as personal and parental characteristics. In contrast, controlling for the influence of unobservable factors potentially correlated with smoking behavior and depression produces smaller estimates. For instance, estimates from a linear regression model augmented with fixed effects suggest that the average male smoker would score 0.84 points higher on the CES-D Scale (95% confidence interval: 0.44, 1.25) than his nonsmoking counterpart; the average female smoker is predicted to score 1.25 points higher on the CES-D Scale (95% confidence interval: 0.75, 1.75) than her nonsmoking counterpart. The authors conclude that, for the average adolescent, the association between smoking and the symptoms of depression can in large part be attributed to the influence of unobservable factors.
作者利用国家青少年健康纵向研究前两波1995 - 1996年的数据发现，在流行病学研究中心抑郁量表（CES - D）上，吸烟的受访者平均得分比不吸烟者高3分。即使在考虑了个人和父母特征等可观察因素之后，这种差距仍然存在。相比之下，控制与吸烟行为和抑郁潜在相关的不可观察因素的影响会得出较小的估计值。例如，一个加入固定效应的线性回归模型的估计表明，平均而言，男性吸烟者在CES - D量表上的得分比不吸烟的同龄人高0.84分（95%置信区间：0.44，1.25）；预计女性吸烟者在CES - D量表上的得分比不吸烟的同龄人高1.25分（95%置信区间：0.75，1.75）。作者得出结论，对于普通青少年来说，吸烟与抑郁症状之间的关联在很大程度上可归因于不可观察因素的影响。
