Table 1.

Definitions of key behavioral economic terms.

Term	Definition
Demand intensity	Level of purchasing of a commodity when its own price is zero; the elevation of the own-price demand/purchasing function relative to the origin.
Demand elasticity	The sensitivity of purchasing to increases in its own price, specified by the slope of the own-price demand/purchasing function. Inelastic demand specifies that large increases in price result in small decreases in purchasing or consumption. Elastic demand specifies that small increases in price produce large decreases in purchasing or consumption.
Substitution/substitutability	A form of product switching and an interaction between two products; traditionally defined as an increase in purchasing of a price-constant product as a result of an increase in the price of an alternative commodity. Can be measured by the slope (cross-price elasticity) of the price-constant purchasing function. Can also be measured as an elevation in purchasing of a price-constant commodity at a fixed-price of the price changing, alternative commodity, seen at the y-intercept (initial intensity) or the upper bound (terminal intensity) of the price-constant function.
Cross-price elasticity	The slope of the price-constant purchasing function over the increase in price of the alternative commodity; defines the degree of substitution/substitutability of a product. A steeper slope indicates greater substitutability.
Initial intensity of substitution	The initial elevation or y-intercept of the price-constant purchasing function at the lowest price of the price-manipulated alternative commodity; a higher y-intercept indicates greater initial intensity of substitution.
Terminal intensity of substitution	The terminal elevation or upper-bound of the price-constant purchasing function at the highest price of the price-manipulation alternative commodity; a higher upper-bound indicates a greater terminal intensity of substitution.