Evaluating of green nudge in the context of sustainable development goals: A meta-analysis

There is an increasing number of studies on nudging, a policy tool of behavioral economics, to overcome environmental problems. These so-called green nudges have been criticized for not being effective enough. This study aims to assess whether the criticisms are justified in the context of the Sustainable Development Goals (SDGs), and to demonstrate how effective green nudges are as a policy tool. The methodology of the thesis is meta-analysis, which allows generalizations to be made by analyzing a large number of studies. The meta-analysis data were collected from a total of 85 green nudges in 59 studies published between 2011 and 2024. The mean effect size calculated with the random effects model was 0.313 [95% CI= (0.261 - 0.365), z = 11.896, p < 0.000]. This result shows that green nudges have a positive effect on pro-environmental behaviors. In addition, three different subgroup analyses were conducted in this study. In the first subgroup analysis, green nudges were analyzed by grouping them according to Sustainable Development Goals. In the second subgroup analysis, green nudges were categorized according to their types. In the last subgroup analysis, digital and face-to-face green nudges were analyzed. According to the overall results of the meta-analysis, green nudge has a medium effect size. Moreover, the true effect size distribution is largely positive. This suggests that green nudges can be an important behavioral policy tool for the SDGs, complementing traditional policy instruments.