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.