The use of feedback to enhance environmental outcomes: a randomised controlled trial of a food waste scheme

Food waste makes up about 20% of general waste that goes to the landfill every year in the UK. Encouraging the public to engage in food waste recycling and separating more food from general waste could help local governments promote a better environment. Appeals to collective norms, by giving people feedback on their street's food waste recycling rate compared with others, could promote recycling. To test this, we carried out a randomised controlled trial in Oldham, Greater Manchester. We randomly assigned 318 streets to a treatment and control group. Households in the treatment group were sent two postcards that provided feedback on how their street performed on food waste recycling compared with the average for their neighbourhood. Participation in the food waste scheme was measured for all households on three occasions: at baseline, and after the receipt of the first- and second-feedback cards. We estimated the effect of our treatment using cross-classified multilevel logistic regression models, controlling for baseline, street size and the interaction of treatment and baseline. We show that feedback had a positive effect on the food waste participation with an effect size of 2.8% compared with a control group that received no treatment.