The Impact of a City-Level Minimum Wage Policy on Supermarket Food Prices by Food Quality Metrics: A Two-Year Follow Up Study
The Impact of a City-Level Minimum Wage Policy on Supermarket Food Prices by Food Quality Metrics: A Two-Year Follow Up Study
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DOI：
10.3390/ijerph16010102
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发表时间：
2019-01-01
影响因子：
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通讯作者：
Otten, Jennifer J.
中科院分区：
文献类型：
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作者：
Buszkiewicz, James;House, Cathy;Otten, Jennifer J.
目的：研究提高最低工资对西雅图超市食品价格在两年内政策实施的影响，总体上和不同食品质量指标的差异。方法：在政策实施前（2015年3月）1个月、政策实施后（2015年5月）1个月、政策实施后（2015年5月）1年、政策实施后（2016年5月）1年、政策实施后2年（2017年5月）4个时间点，获取西雅图6家大型连锁超市（CPHN）购物篮中106种食品的价格（干预）和金县同一连锁超市（对照）。所有食品的价格都被标准化并转换为每100千卡的价格。食品质量指标被用来探索(a)美国农业部定义的食品类别的潜在差异价格上涨；(b) NOVA食品加工类别，(c)基于营养丰富食品指数9.3的营养密度四分位数。独立的差异中差异线性回归模型具有稳健的标准误差，检查了每100千卡的价格差异，按连锁店聚类，并按每个食品质量指标分层。结果：西雅图最低工资政策没有导致整体市场篮子价格的变化。此外，美国农业部食品组、食品加工或营养密度类别没有检测到最低工资的影响。结论：西雅图最低工资政策实施2年后，整体或分类别上调至15美元/小时后，当地超市食品价格并未受到影响。如果工资上涨，而超市价格保持不变，低收入工人或许能够负担得起更高质量的饮食。
Objective: To examine the effects of increasing minimum wage on supermarket food prices in Seattle over 2 years of policy implementation, overall and differentially across food quality metrics. Methods: Prices for the UW Center for Public Health Nutrition (CPHN) market basket of 106 foods were obtained for 6 large supermarket chain stores in Seattle (intervention) and for the same chain stores in King County (control) at four time points: 1-month pre- (March 2015), 1-month post- (May 2015), 1-year post- (May 2016), and 2-years post-policy implementation (May 2017). Prices for all food items were standardized and converted to price per 100 kcal. Food quality metrics were used to explore potential differential price increases by (a) food groups, as defined by US Department of Agriculture; (b) NOVA food processing categories, and (c) nutrient density quartiles, based on the Nutrient Rich Foods Index 9.3. Separate difference-in-differences linear regression models with robust standard errors, examined price differences per 100 kcal overall, clustered by store chain, and stratified by each food quality metric. Results: There were no overall market basket price changes attributable to Seattle's minimum wage policy. Moreover, no minimum wage effect was detected by USDA food group, food processing, or nutrient density categories. Conclusions: Local area supermarket food prices were not impacted by Seattle's minimum wage policy 2 years into policy implementation and after the first increase to $15/h overall or by sub-classification. Low-income workers may be able to afford higher quality diets if wages increase yet supermarket prices stay the same.