Bridging the gap between self-assessments and measured household food waste: A hybrid valuation approach
. Waste Management 2019
, 259 - 270. Abstract
Great effort is invested in mapping the extent of household food waste and its main determinants. However, food waste valuation remains a challenging task. Valuation methods can be divided roughly into objective measurements that are based on physical waste surveys, and subjective self-assessments that are based on diaries or questionnaires. Self-assessment methods have been more popular than food waste measurement because they are less costly. The goal of this paper is to empirically test whether self-assessments can accurately reflect objective measurement. To answer this question, we implemented a hybrid valuation approach by integrating and comparing three methods: a self-assessment questionnaire, a physical waste survey, and a food expenditure survey. Self-assessments slightly underestimated measured food waste proportion (13.7% vs. 16.3%, respectively). The results also show a positive, yet, not very strong correlation between the measures and the self-assessments of unconsumed and partly consumed avoidable food waste in most food categories. Self-assessments of monetary losses were €42.07 per household per month on average, overestimating calculated losses of €25.74 on average. Our findings question the validity of self-assessments. The current paper demonstrates the questionable nature of the implicit assumption that self-assessment reflects the true level of food waste and suggests a rigorous method for exploring this relation.
Exploring the Drivers behind Self-Reported and Measured Food Wastage
. Sustainability 2019
Understanding households’ food waste drivers is crucial for forming a coherent policy to meet the sustainable development goals. However, current studies have documented mixed evidence regarding food waste determinants. Most studies have relied on self-reports, assuming they reflect actual behaviors. This study applies a structural equation model that evaluates both self-reported and measured food wastage, and how they are affected by different households’ attributes, attitudes, and behaviors. As such, it also provides a test for the underlying logic that self-reports are a proxy for actual food waste. Results show that measured food wastage is, at best, weakly correlated with self-reports. Moreover, drivers affecting self-reported and measured food wastage are not necessarily the same. Household size affects only measured food wastage. Source separation behavior negatively affects self-reported and measured food wastage, while environmental attitudes have a negative effect only on self-reports. Meal planning, unplanned shopping, and food purchased have no impact on self-reported and measured food wastage. The relation between self-reported and actual food waste and their drivers are even less understood than we thought. The distinction between self-reports and actual waste is crucial for follow-up research on this subject as well as assessing policy measures.