Explicit comparison of se¨eral objects imposes a shared context for their judgment
and ¨aluation. When the objects belong to different categories, comparisons and
isolated ¨aluations can yield discrepant results. Differences between the modes of
¨aluation are found both in dollar measures and in ratings. Table 3 presents
preliminary tests of this hypothesis, drawn from two different studies. The same
pair of issues was used in both studies: damage to coral reefs caused by cyanide
fishing in Asia, and increased incidence of multiple myeloma among the elderly.
We surmised that the latter issue would be perceived as a fairly minor public
health problem, whereas a threat to coral reefs would appear significant in an
ecological context. We also surmised that public health problems would be assigned
a higher general priority than ecological problems, but that this priority
would only become relevant in a direct comparison.