Korea Insurance Research Institutes, Seoul, Korea.
Popul Health Manag. 2011 Dec;14(6):307-15. doi: 10.1089/pop.2010.0071. Epub 2011 Aug 9.
Whereas some studies show statistically significant linear associations between consumption at full-service restaurants and consumer incomes, studies of fast-food restaurants fail to find statistically significant linear associations. In this study, nationally representative data were drawn from the 1994-1996 Continuing Survey of Food Intakes by Individuals and the accompanying Diet and Health Knowledge Survey. The sample contained 4972 individuals who were 21 years of age or older. Dependent variables measured number of restaurant visits on 2 nonconsecutive days. Income was total annual household income. Control variables reflected sociodemographic, economic, lifestyle, and attitudinal variables. To capture possible curvilinear relationships between income and food consumption, we analyzed frequency distributions, regressions on full samples including income squared, and we divided samples into above- and below-average income groups. Zero-inflated negative binomial regressions accounted for excessive zeros within dependent variables. We found that fast-food restaurants were "normal goods" for below-average income, but "inferior goods" for above-average income, whereas full-service restaurants were "normal" for virtually all income levels. Earlier studies were flawed because they only tested for linear associations. Our results have implications for the poverty and obesity debate.
虽然有些研究表明，在全方位服务的餐厅消费与消费者收入之间存在着统计学上显著的线性关系，但对快餐店的研究却没有发现统计学上显著的线性关系。在这项研究中，从 1994-1996 年个人饮食摄入量连续调查和伴随的饮食与健康知识调查中提取了全国代表性数据。样本包含 4972 名年龄在 21 岁或以上的个体。因变量衡量了两天内餐厅用餐的次数。收入是家庭总收入。控制变量反映了社会人口统计学、经济、生活方式和态度变量。为了捕捉收入与食物消费之间可能存在的曲线关系，我们分析了频率分布，对包括收入平方的全部样本进行了回归，我们还将样本分为高于平均收入和低于平均收入组。为了处理因变量中过多的零值，我们采用了零膨胀负二项回归。我们发现，对于低收入群体来说，快餐店是“正常商品”，但对于高收入群体来说，快餐店是“劣质商品”，而全方位服务餐厅对于几乎所有收入水平来说都是“正常”的。早期的研究存在缺陷，因为它们只测试了线性关系。我们的研究结果对贫困和肥胖问题的辩论具有启示意义。
