Task: Text Categorization
Input (English): Slutsky's equation relates two functions for this quantity. As price increases, this quantity increases for lower-priced goods in the substitution effect. The "Hicksian" variety of this quantity is often contrasted with its "Marshallian" type. Although it increases with price for Veblen goods, this quantity is usually (*) inversely correlated with price. For 10 points, name this concept, often paired with supply, which represents the public's desire for a product.
Output (English): Social Science