Yang Yanliang, Davis George C, Muth Mary K
Department of Agriculture and Applied Economics, College of Agriculture and Life Science, Virginia Tech, Blacksburg, VA; and
Department of Agriculture and Applied Economics, College of Agriculture and Life Science, Virginia Tech, Blacksburg, VA; and.
Am J Clin Nutr. 2015 Jul;102(1):165-71. doi: 10.3945/ajcn.114.101444. Epub 2015 May 20.
An ongoing debate in the literature is how to measure the price of food. Most analyses have not considered the value of time in measuring the price of food. Whether or not the value of time is included in measuring the price of a food may have important implications for classifying foods based on their relative cost.
The purpose of this article is to compare prices that exclude time (time-exclusive price) with prices that include time (time-inclusive price) for 2 types of home foods: home foods using basic ingredients (home recipes) vs. home foods using more processed ingredients (processed recipes). The time-inclusive and time-exclusive prices are compared to determine whether the time-exclusive prices in isolation may mislead in drawing inferences regarding the relative prices of foods.
We calculated the time-exclusive price and time-inclusive price of 100 home recipes and 143 processed recipes and then categorized them into 5 standard food groups: grains, proteins, vegetables, fruit, and dairy. We then examined the relation between the time-exclusive prices and the time-inclusive prices and dietary recommendations.
For any food group, the processed food time-inclusive price was always less than the home recipe time-inclusive price, even if the processed food's time-exclusive price was more expensive. Time-inclusive prices for home recipes were especially higher for the more time-intensive food groups, such as grains, vegetables, and fruit, which are generally underconsumed relative to the guidelines.
Focusing only on the sticker price of a food and ignoring the time cost may lead to different conclusions about relative prices and policy recommendations than when the time cost is included.
文献中正在进行的一场辩论是如何衡量食品价格。大多数分析在衡量食品价格时未考虑时间价值。在衡量食品价格时是否包含时间价值可能对根据食品相对成本对食品进行分类具有重要意义。
本文的目的是比较两类家庭食品（使用基本食材的家庭食品（家庭食谱）与使用更多加工食材的家庭食品（加工食谱））排除时间的价格（不含时间价格）和包含时间的价格（含时间价格）。比较含时间价格和不含时间价格，以确定单独的不含时间价格在推断食品相对价格时是否可能产生误导。
我们计算了100种家庭食谱和143种加工食谱的不含时间价格和含时间价格，然后将它们分为5个标准食物组：谷物、蛋白质、蔬菜、水果和乳制品。然后我们研究了不含时间价格与含时间价格之间的关系以及饮食建议。
对于任何食物组，加工食品的含时间价格总是低于家庭食谱的含时间价格，即使加工食品的不含时间价格更高。家庭食谱的含时间价格在谷物、蔬菜和水果等耗时较长的食物组中尤其更高，而这些食物组相对于指南的摄入量通常不足。
只关注食品的标价而忽略时间成本可能会导致与包含时间成本时关于相对价格和政策建议的不同结论。
