If I make $40,000 and my twin brother makes $42,000 at a job that is identical to mine in all respects except for a 1 percent greater chance of death, then an economist assumes that the $2,000 difference is a premium my twin brother requires to accept the riskier job. If he requires $2,000 for a 1 percent greater risk, then I can infer that he is placing a value on his life of $2,000 x (1 ÷ 0.01), or $200,000. There are problems with this approach. University of Wyoming professors Jason Shogren and Tommy Stamland argue that nearly all revealed preference studies are biased upwards to some degree. They observe that the wage at a particular job is just enough to entice the marginal worker. The other workers require less some limit money to accept the risk.
On the other hand, a downward bias is that there are lots of people who did NOT take the job because they require even more money to accept that risk.