Similar results have been obtained in other applications of the quantity design.
In an early study using this design, Kahneman and Knetsch see Kahneman, 1986.
found that Toronto residents were willing to pay only a little more to clean up all
the polluted lakes in Ontario than to clean up polluted lakes in a particular region
of Ontario. McFadden and Leonard 1993. reported that residents in four western
states were willing to pay only 28% more to protect all 57 wilderness areas in those
states than to protect a single area. Jones-Lee et al. 1995. found that the SWTP of
UK respondents for a program to reduce the risk of non-fatal road injuries
increased by only 29% when the number of prevented injuries was increased by a
factor of three. Laboratory studies show similar insensitivity to the quantity of the
good. Baron and Greene 1996, experiment 8., for instance, found no effect on
SWTP of varying the number of lives saved by a factor of 10.