income. The following discussion reviews evidence identified by the committee on components of the SNAP benefit formula and the factors that influence them, and assesses their relationship to the purchasing power of SNAP allotments.

Maximum Benefit Guarantee

Entitlement to SNAP benefits is derived from the cost of the Thrifty Food Plan (TFP) for a family of four. The TFP is based on the cost of purchasing foods consumed by individuals in four age-gender groups. The U.S. Department of Agriculture (USDA) developed four food plans (described in Chapter 2) based on market baskets of food that can provide a diet meeting dietary recommendations for individuals.1 The foods in each market basket are based on current consumption patterns, dietary recommendations, and food composition data and prices. In determining SNAP benefits, the following age-gender groups are used: a male and a female aged 19-50, a child aged 6-8, and a child aged 9-11. In 2006, the market baskets were revised to reflect the Dietary Reference Intakes (IOM, 1997, 1998, 2000, 2001, 2005a,b), the 2005 Dietary Guidelines for Americans (DGA) (USDA and HHS, 2005), the 2005 MyPyramid Food Guidance System (USDA, 2005), and changes in food prices and consumption patterns.

Household Size and the Benefit Level

As noted in Chapter 2, the TFP is designed for a reference family of two adults and two children, and the cost is then adjusted for families of different sizes to reflect economies of scale in food purchases. As described in Box 5-1, relative to the per-person benefit for a family of four, the perperson benefit is increased by 5 percent for a family of three, by 10 percent for a family of two, and by 20 percent for a family of one. Per-person benefits are reduced by 5 percent for families with five or six members and by 10 percent for families with seven or more members. These adjustment factors do not appear to be in line with differential spending patterns for food across families of different sizes, however. According to calculations from the 2010 Consumer Expenditure Survey, per-person expenditures on food are 11 percent higher for families of three than for families of four; families of two and one spend 36 and 57 percent, respectively, more per person than families of four. When restricted to purchases of food consumed at home, the numbers are slightly different and suggest that a more realistic economies-of-scale multiplier would be 44 percent for a one-person family,


1Detailed information on the plans is available at (accessed March 11, 2013).

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