We present data of a contingent valuation survey, testing the effect of evaluation
mode on the monetary valuation of preventing road accidents. Half of the interviewees
was asked to state their willingness to pay (WTP) to reduce the risk of having
only 1 type of injury (separate evaluation, SE), and the other half of the sample
was asked to state their WTP for 4 types of injuries evaluated simultaneously (joint
evaluation, JE). In the SE group, we observed lack of sensitivity to scope while in
the JE group WTP increased with the severity of the injury prevented. However,
WTP values in this group were subject to context effects. Our results suggest that
the traditional explanation of the disparity between SE and JE, namely, the so‐called
“evaluability,” does not apply here. The paper presents new explanations based on
the role of preference imprecision.
