Household size and the cost of nutritionally equivalent diets

Economy of scale factors were developed in 1975 and have since been utilized as household size adjustment factors in estimating household costs of US Department of Agriculture (USDA) food plans. As such, these adjustment factors have a direct impact on the Food Stamp Program coupon allotments. In the present study, the stability of these factors over time was assessed, and the impact of diet quality measures in determining the adjustment factors was investigated. The reported household scale factors, estimated using regression analyses and the Nationwide Food Consumption Survey, Survey of Food Consumption in Low-Income Households, 1977-78, varied somewhat from former estimates and were found to be highly dependent on the diet quality measures incorporated in the analysis. Incorporation of several diet quality variables as well as partition specific means are recommended for determining household size adjustment factors to be used in estimating household costs of USDA food plans.