The findings obtained in the embedding design unequivocally violate the add-up
rule. For example, Kemp and Maxwell 1993. found that SWTP for protection from
oil spills off the coast of Alaska was $85 when the good was considered on its own,
but only $0.29 when it was derived as an allocation of SWTP for a more inclusive
category environmental protection programs.. Kahneman and Knetsch 1992.
reported similar findings.