The quality of the results that are obtained by the contingent valuation method (CVM)
and choice experiments (CEs) is frequently questioned because of the potential
occurrence of scope insensitivity (also called embedding effect, part-whole bias, or
nesting). This is perceived to bias the survey results, if not to cast doubt on contingent
valuation procedures in general. Embedding was first discussed in the environmental
evaluation literature (e.g., Fischhoff et al. 1993; Loomis et al. 1993; Sælensminde
2003). It refers to the observation that estimated willingness to pay (WTP) does not
sufficiently vary with the size of the good being evaluated (Kahneman and Knetsch
1992). But also the term scope insensitivity is used (Foster and Mourato 2003;
Heberlein et al. 2005; Olsen et al. 2004).