Identifying the scope effect on a meta-analysis of biodiversity valuation studies Elena Ojea a, *, Maria L. Loureiro b,1 a Basque Centre for Climate Change (BC3), Alameda Urquijo 4, 4-1, 48008 Bilbao, Bizkaia, Spain b Universidade de Santiago de Compostela, Departamento de Fundamentos da Ana ´lise Econo ´mica, Facultade de Ciencias Econo ´micas e Empresariais, Campus Universitario Norte, 15782 Santiago de Compostela, Spain 1. Introduction Contingent valuation (hereafter CV) is a popular approach to assessing environmental values in the absence of real markets. This method is especially relevant for its ability to estimate non-use values that could not otherwise be measured. However, since its appearance, it has received much criticism over biases and implementation problems. One of the major criticisms leveled at the method is its insensitivity to the size or amount of the good being valued (Arrow et al., 1993). This problem has been Resource and Energy Economics 33 (2011) 706–724 ARTICLE INFO Article history: Received 19 October 2010 Received in revised form 23 February 2011 Accepted 1 March 2011 Available online 8 March 2011 JEL classification: Q50 Q20 Keywords: Biodiversity Contingent valuation Ecosystems Meta-analysis Scope test ABSTRACT Insensitivity to scope is an issue of much debate in contingent valuation (CV) even today. Although the literature about insensi- tivity to scope is abundant, the reasons for it are not yet well known. Through a meta-analysis of CV studies of biodiversity, the treatment of the different possible measures of the quantity of the good is explored in relation to scope sensitivity. Overall, the findings suggest that CV results are sensitive to the amount of the good being valued, although the result depends on how the environmental change is measured. Results support the use of absolute sizes when conducting CV studies. ß 2011 Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +34 944014690. E-mail addresses: elena.ojea@bc3research.org (E. Ojea), maria.loureiro@usc.es (M.L. Loureiro). 1 Tel.: +34 981563100x14337. Contents lists available at ScienceDirect Resource and Energy Economics journal homepage: www.elsevier.com/locate/ree 0928-7655/$ – see front matter ß 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.reseneeco.2011.03.002