Willingness-to-pay for precautionary control of microplastics, a comparison of hybrid choice models

ABSTRACT

What are people willing to pay to reduce the uncertainty about the effects of microplastics? We examine this question in two ways. Firstly, using two contingent valuation questions, we elicit willingness to pay (WTP) to (a) reduce uncertainty about the potential adverse consequences of microplastic pollution, and (b) to reduce the release of microplastics to the marine environment. WTP was elicited from a representative sample of UK adults in 2020. Comparing WTP for these two scenarios suggests that respondents prefer resolving irreversibility over resolving uncertainty. Secondly, we use a hybrid choice model to show that latent precautionary attitudes exert a strong positive effect on WTP. Overall, respondents indicated a preference for resolving the uncertainty about microplastics by implementing abatement measures immediately. Given that policymakers are increasingly concerned about the potential for adverse environmental and health effects of microplastics in the marine environment, this paper suggests that the precautionary principle has strong support at the respondent level.

KEYWORDS:

• Precaution
• hybrid choice models
• willingness-to-pay
• microplastics

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The anonymised survey data and replication R code is freely available from the authors GitHub repository: https://github.com/pmpk20/PhDHybridChoiceModelPaper

Notes

1 Microplastics are defined as polymer containing particles up to a maximum of five milometers in diameter (ECHA, 2019).

2 It is currently fair to assume that microplastics are irreversibly released given that there is no practical or cost-effective method of recovering microplastics from the marine environment presently available.

3 There is a wider literature on uncertainty and mitigation in climate change and the interested reader is directed to Alfred (2012) among others.

4 The pre-testing of the survey took around three months and used a relatively small pool of potential respondents. Experts were consulted on the scientific effects of microplastics. These included toxicologists, chemists, environmental scientists, industry experts, policymakers and economists. Ten short interviews using the talk-aloud method were undertaken with potential respondents to understand how they evaluated the survey. Finally, a small pilot of 53 respondents using convenience sampling was undertaken. Multiple changes were made to the valuation questions to increase incentive compatibility and plausibility, primarily through scenario text and payment vehicle.

5 Question Two actually used the double-bound dichotomous choice format but we omit that discussion here to focus on attitudes towards WTP.

6 While Vij and Walker (2016) argued that linearly including attitudinal indicators raises the possibility of endogeneity, Budziński and Czajkowski (2018) were cautious on whether the HCM truly corrected for endogeneity.

7 Replication code and data are freely available. See Data Availability Statement.

8 We simulated individual WTP using the Krinsky-Robb bootstrap function in the R DCChoice package (Nakatani et al, 2021).

9 WTP for welfare calculations should still be based on the simpler bid-only probit model.

10 A plot of the distribution of the estimated latent variable from both models is available in the Appendix.

11 One anonymous reviewer suggested that the perceived effectiveness of each policy option may influence WTP. Although we do not observe this directly, respondent certainty about each question is measured. For example, the greater certainty for Question Two may indicate that respondents were more confident in this scenario being effective. This may then begin to explain the increased WTP. However, certainty may also measure scenario understanding or preference for immediate abatement, and so there is some measurement error associated with this line of reasoning.

12 I am thankful to an anonymous reviewer for discussing Chorus and Kroesen (2014) excellent work discussing the HCM in transport models.

Additional information

Funding

Financial support acknowledged for PhD studentship (University of Bath), and data collection (Environment Agency).