title: The Need for Formal Evidence Synthesis in Food Policy: A Case Study of Willingness-to-Pay.
abstract: Meta-analysis is increasingly utilised in the understanding of consumer behaviour, including in relation to farm animal welfare. However, the issue of publication bias has received little attention. As willingness-to-pay (WTP) is widely used in policy, it is important to explore publication bias. This research aimed to evaluate publication bias in WTP, specifically public WTP for farm animal welfare. A systematic review of four databases yielded 54 studies for random effects meta-analysis. Publication bias was assessed by the Egger test, rank test, contour-enhanced funnel plots, and the Vevea and Hedges weight-function model. Results consistently indicated the presence of publication bias, highlighting an overestimation of WTP for farm animal welfare. Stakeholders should be wary of WTP estimates that have not been critically evaluated for publication bias.
authors.affiliation: School of Agriculture Food and Rural Development, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK. b.clark@newcastle.ac.uk.
authors.forename: Beth
authors.initials: B
authors.lastname: Clark
authors.affiliation: School of Agriculture Food and Rural Development, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK. lynn.frewer@newcastle.ac.uk.
authors.forename: Lynn J
authors.initials: LJ
authors.lastname: Frewer
authors.affiliation: School of Agriculture Food and Rural Development, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK. luca.panzone@newcastle.ac.uk.
authors.forename: Luca A
authors.initials: LA
authors.lastname: Panzone
authors.affiliation: School of Agriculture Food and Rural Development, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK. gavin.stewart@newcastle.ac.uk.
authors.forename: Gavin B
authors.initials: GB
authors.lastname: Stewart
keywords: farm animal welfare; meta-analysis; publication bias; willingness-to-pay