The Quarter-Waste Method
Gauging Food Waste Faster and More Accurately!
The Quarter-Waste Method is a quick and reliable way to evaluate how students react to changes in school lunches by measuring food waste
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Hanks, Andrew S., David Just and Brian Wansink. (2014). Reliability and Accuracy of Real-Time Visualization Techniques for Measuring School Cafeteria Tray Waste: Validating the Quarter-Waste Method. Journal of the Academy of Nutrition and Dietetics, 114(3), 470-474. doi:10.1016/j.jand.2013.08.013
School lunches are becoming increasingly healthy as more whole grains, fruits, and vegetables appear on the lunch line, but are kids actually eating these healthy options? To determine if these foods are winding up in kids’ stomachs or in garbage cans, schools need to be able to measure food waste quickly and accurately. Though weighing cafeteria tray waste is the most precise method of measurement, it is time consuming and costly, which gives fast and simple visual methods of waste measurement the advantage.
At the Cornell Center for Behaviral Economics in Child Nutrition Programs (home of the Smarter Lunchrooms Movement), researchers Drew Hanks, Brian Wansink and David Just put several visual methods to the test to determine which would provide the most accurate waste measurements quickly and inexpensively, relative to the weighing method. They examined tray waste from 197 elementary school students using three visual methods:
- Half-Waste Method: Researchers estimated whether All, Some, or None of a particular item was wasted.
- Quarter-Waste Method: Researchers estimated whether All, ¾, ½, or ¼ of a food was wasted.
- Photograph Method: Researchers photographed each tray and then later estimated how much food was wasted in 10% increments.
The Quarter-Waste method proved to be the most accurate, with a reliability measure of 0.90. The half-waste method only had a reliability measure of 0.83, while the photograph method was found to be the least accurate (with a measure of just 0.48). The downfall of the photograph method was the inability to touch packaged food items; a photograph cannot show how much milk is left in a carton or how much food is left in a snack package.
One of the main benefits of the visual Quarter-Waste method is time. According to the researchers, weighing food waste took about 30 seconds per tray, while the Quarter- and Half-Waste took about 1/5th of the time. This difference in measurement time is most apparent when measuring the trays of a large student body.
When performing your own tray-waste observations, the researchers recommend keeping the measurement process as unobtrusive as possible. Instruct students to leave trays in inconspicuous locations in the cafeteria to avoid drawing attention to the measuring process. If students ask why researchers are present, general responses such as “We are collecting information on your cafeteria” can provide students with an answer without biasing their food consumption.
Waste measurement via the Quarter-Waste Method can be a quick and reliable way to evaluate how students react to nutritional interventions, new food products, or lunch line rearrangements by measuring how much food they devour or discard!
For more about the Smarter Lunchroom stategies, visit: smarterlunchrooms.org