Willingness to pay for cleaning up beach litter: A meta-analysis.

At the global level, the UN 2030 Agenda for Sustainable Development Goal 14 calls for action to significantly reduce marine litter pollution by 2025. To understand the non-market benefits of removing marine litter, researchers have conducted numerous studies on Willingness to Pay (WTP) for reductions in beach litter. This paper estimates the overall effect size of WTP for a worldwide dataset of 63 primary studies over 22 years by applying a meta-regression technique to assess the variability in WTP estimates. The results show an annual mean effect size of $US0.71 (or $US35.29) per person for a 1 % (for a corresponding 50 %) reduction in all types of beach litter. The observed heterogeneity is associated with WTP elicitation methods, beach attributes, geographic locations, and per-capita income. This study yields valuable information for policy makers to develop cost-effective policies and recommends standardised measurements to benchmark changes in marine litter pollution.

Willingness to pay for socially responsible products: A meta-analysis of coffee ecolabelling.

Primary studies estimate consumers' willingness to pay for a single or a couple of coffee ecolabelling in a single country and occasionally across countries. The estimates are not beyond explaining consumers' willingness to pay for a specific attribute in that particular study area. This creates uncertainty in disentangling heterogeneity in the effect size within the same country and across countries which can be associated with publication bias and/or other factors. We apply a meta-analysis that combines individual willingness to pay (n = 97) from 22 primary studies to estimate average effect size for each attribute and explore factors that explain heterogeneity in the effect size in the last 15 years. Our descriptive analysis results designate that consumers' willingness to pay for a pound of Organic, Country of Origin Labeling, and Fairtrade coffee is positive and significant. The meta-model results show that Organic attribute is the most important factor that affects willingness to pay for eco-coffee. Compared to other stated preference methods, choice experiment has the potential to reduce hypothetical bias and precisely estimate the effect size. The difference in the effect size across regions indicates consumers' preference heterogeneity for coffee ecolabelling. In general, despite the debate that the existence of multiple ecolabelling in the market may cause a decline in consumers' trust and willingness to pay overtime, our study concludes that consumers' purchase behavior in selected countries is pro-eco-coffee.