Public health taxes on less healthy food and beverage products have been shown to be effective in various settings. However, it is unclear if observed reductions in the quantity of taxed products purchased is a result of price increases due to the tax or the accompanying messaging and if the effects are influenced by the level of support for such taxes within the population. 941 adults residing in Singapore were randomized and asked to shop in one of four versions of a fully functional on-line experimental grocery store: 1) no tax control; 2) implicit tax showing only post-tax prices (i.e., 20 % higher than control prices) on high-in-calorie products; 3) fake tax showing pre-tax prices and a label falsely indicating that the price includes a 20 % tax on high-in-calorie products; and 4) explicit tax showing the same label as in 3) and an actual 20 % price increase applied to the high-in-calorie products. The proportion of high-in-calorie products purchased was 14 % in the control arm. We were unable to reject the null hypothesis of no effect in the implicit tax arm compared to control (0.08, 95 % CI -3.31 to 1.77) or in the fake tax arm compared to the control (2.59, 95 % CI -5.04 to 0.00) but observed a statistically significant 3.35 percentage point decrease (95 % CI -6.01 to -0.5) in the explicit tax arm compared to control. We were unable to reject the null hypothesis of no effect in any of the outcomes related to diet quality. Individuals who support the tax showed greater responsiveness to the explicit and fake taxes compared to those who do not (price elasticities of demand of -1.38 and -0.51 respectively). Results suggest that reductions in the proportions of high-in-calorie products purchased may be largely attributable to explicit messaging rather than to price increases. However, even when effective, policymakers should recognize that changes in purchasing patterns may not improve diet quality and that results may not generalize to other areas where levels of support differ.

中文翻译：

---

隐性税和显性税对购买“高热量”产品的影响：一项随机对照试验。

事实证明，对不健康食品和饮料产品的公共卫生税在各种情况下都是有效的。但是，目前尚不清楚观察到的购买的税收产品数量的减少是否是由于税收或伴随的消息传递而导致的价格上涨的结果，以及这种影响是否受到人口中对此类税收的支持程度的影响。941名居住在新加坡的成年人被随机分配，并被要求在功能齐全的在线实验杂货店的四个版本之一中购物：1）没有税收管制；2）隐性税仅显示高热量产品的税后价格（即比控制价格高20％）；3）伪造的税款，显示税前价格，以及带有标签的标签，错误地表明该价格包括高热量产品的20％税；4）显示与3）相同标签的明确税项，并且对高热量产品实际提高了20％的价格。购买的高热量产品比例在对照组中为14％。我们无法拒绝隐性税收部门与对照组相比（0.08，95％CI -3.31至1.77）或假税收部门与对照组相比（2.59，95％CI -5.04至0.00）无效的零假设。 ），但与对照组相比，在显性税项中观察到统计学上显着的下降3.35个百分点（95％CI -6.01至-0.5）。我们无法拒绝与饮食质量有关的任何结果均无效的零假设。与不支持税的人相比，支持不税的人表现出对显性税和假税的更大反应（需求的价格弹性分别为-1.38和-0.51）。结果表明，购买的高热量产品所占比例的下降可能主要归因于明确的信息传递，而不是价格上涨。但是，即使有效，决策者也应该认识到购买方式的改变可能不会改善饮食质量，其结果也可能不会推广到支持水平不同的其他领域。