Thinking and Deciding

328 UTILITY MEASUREMENT
is equivalent to ten years in pain. This leads to inconsistent utility assessments, but
it may be perfectly rational. It may be that the things that people want to do with
their lives when death is imminent are different things than they want to do when
they have longer to live. People with a few weeks to live may focus more on getting
their affairs in order for the benefit of their survivors — insofar as they can focus on
anything — and this may not depend much on the state of their health. For practical
purposes of measurement, this problem may be avoidable by using longer durations.
Even with longer durations, though, some people claim to be unwilling to make
any sacrifice of duration of life for quality of life, even when the quality difference
is large, as determined by direct rating (O’Leary, Fairclough, Jankowski, and Weeks,
1995). Such people may be following a simple rule of giving priority to life rather
than thinking of what they (or others) might do with their lives over the periods at
issue.
Another result that is disturbing for the time-tradeoff method is a kind of preference
reversal (Stalmeier, Wakker, and Bezembinder, 1997). When people are given a
choice between living ten years with five days per week of migraine headaches (described
thoroughly to them) and twenty years with five days per week of migraine,
they prefer the shorter life span. This might be a rational choice if you thought that
the ten years would give you a chance to tie up various projects and prepare for
death but that, from a strictly experiential point of view, this condition would otherwise
be worse than death. Yet, the same people were asked how many years of
good health was equal to these two situations, and they gave longer durations for the
twenty years than for the ten years, as if asking about years called attention to the
duration of the two states rather than the severity of the condition. The time tradeoff
may induce people to to attend to duration more than would be consistent with their
overall goals.
A closely related method counts people instead of time intervals. Suppose you
have a choice of curing 100 people of cough or X people of headache. At what
number X would you be indifferent? If you say twenty five, then we infer that
the utility of curing cough is a quarter of that utility of curing headache, in your
judgment. Or, you have a choice of curing 100 people of chest pain or saving Y
people from imminent death. At what value of Y are you indifferent. If you say
thirty, then we conclude that chest pain is .3 of the distance between normal health
and death, so that it would have a utility of .7 on the scale we’ve been using. This
method is called the person tradeoff.
This method assumes that we can add utility across people. This is the assumption
of utilitarian philosophy. We shall examine this idea in Chapter 16. Part of the
problem with the person tradeoff is that people do not accept the assumption. For
example, many people think that is equally good to save the life of 100 people who
will be paralyzed after they are saved as it is to save the life of 100 people who will
be normal after they are saved (Ubel, Richardson, and Pinto Priades, 1999). This
implies that paralysis has a utility of 1 on the usual scale: It is as good as being normal.
When the subjects are asked to compare saving 100 people from paralysis and
saving X people from death, they give intermediate values for X, around 50. These