有機性廃棄物のリサイクル普及効果分析: ランダム化対照試行を用いたバイオマス循環システム支援方策の政策的含意

食品由来の有機性廃棄物のリサイクルを普及を促すための施策効果をランダム化対照試行を用いた実証実験を行った. 道レベルの有機 性廃棄物リサイクル普及率を各世帯へのフィードバックとしてポストカードで世帯に送付することで, 同じ「道」に住む世帯で, 規範が活性化して帰属意識を刺 激し, 集団間の対抗意識ならびに集団内のリサイクリング協同意識が高まることが制度普及へ与える効果検証を行った. その結果, 地域の社会経済水準が参加に 与える影響があり, また, 帰属意識は, 「道」の長さが影響していること, 道のリサイクリング率をフィードバックとしたカードが与える正の普及効果があり, 政策誘導施策として有効であることが示された.A Randomised Control Trial (RCT) asked whether the use of tailored feedback could be used to encourage participation in a kerbside food waste recycling scheme in Oldham, Greater Manchester. The rationale for the trial was that most people underestimate the extent to which their peers engage in pro-social behaviour and compare their own behaviour to these under-estimates. 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 to 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. Normative feedback can have a positive impact on participation but the impact is small. The impact was greater on streets that were small (with between 8 and 30 households) and where the baseline was low. We also estimated that with the feedback postcard nudge, we can reduce food waste which can contribute 5,332 pounds worth less of food waste in the area. From the trials, feedback had the positive cumulative effect on the participation rate.