Household versus individual valuation: what’s the difference?

Standard practice in stated preference typically blurs the distinction between household and individual responses, but without a clear theoretical or empirical justification for this approach. To date there have been no empirical tests of whether values for say a two adult household elicited by interviewing one randomly selected adult are the same as the values generated by interviewing both adults simultaneously. Using cohabiting couples, we conduct a choice experiment field study valuing reductions in dietary health risks. In one treatment a random individual is chosen from the couple and interviewed alone; in the other treatment, both partners are questioned jointly. We find significant differences in household values calculated from joint as opposed to individual responses, with further variation between the values elicited from men and women. Our results question the assumption, implicit in common practice, that differences between individually and jointly elicited estimates of household values can effectively be ignored.