A STATISTICAL METHOD FOR MEASURING ‘MARGINAL UTILITY” 177 
Nor does it seem likely that this want-for-one-more food unit 
is dependent, in any important degree, on circumstances outside 
the budget such as the character of the neighbors’ rations. As to 
housing, on the other hand, the want-for-one-more unit will prob- 
ably be appreciably affected by one’s neighbors’ standards. The 
only way to eliminate this influence is to assume that the same 
general social standards apply in Oddland as in Evenland. Prob- 
ably, in actual practice, the chief difficulty in the way of accurate 
statistical measurement will consist in getting cases differing in 
income without differing greatly in the influence of social environ- 
ment on the problem. As I see it, this is the only difficulty of 
importance. 
With this assumed, however, I cannot see any reason to doubt 
the substantial truth of the proposition that, when the adjust- 
ment of housing accommodation to prices is effective in both 
countries, the desire for one more housing unit is the same in 
Cases 3 and 2. 
Equation (2) Interpreted 
We now ask anew, in what sense does the equation, W; F;— 
Wy F,, mean that the family wants one more unit of the ration in 
Case 1 exactly as intensely as the 2nd family wants one more 
unit added to the same, or equivalent, ration in Case 2? Putting 
this equation in the form ol = 7 and remembering that the W's 
2 1 
are per dollar, we see it means that our families’ wants-for-one- 
more dollar’s worth of the ration common to Cases 1 and 2 are 
inversely as the price indexes in the two countries. Or again, by 
using the reciprocal of this price index as an index of the 
purchasing power of the dollar, and so putting the equation in 
the form: 
Wy _ UF; 
Wa . 1/F, 
he BLE 
we may say that the want-for-one-more dollar, or for one more 
dollar’s worth of the food ration, varies directly with the pur- 
chasing power (in terms of food) of the dollar. In our imaginary 
calculations the common food ration of Cases 1 and 2 costs $400 
in Oddland and $300 in Evenland, the price index being, in the 
two Cases, as 4 to 3, or the purchasing power of the dollar as