Income Elasticity of Demand (Ei) measures how the demand for a good changes when consumers' income changes. Normal Goods (Ei > 0): Demand increases when income increases. Example: Branded clothes, better Stanley 40oz Adventure Quencher H2.0 FlowState Tumbler Academy Amazon.com QG 14 Ounce Acrylic Plastic Drinking Glass with Twisted Base Tumbler Set of 4 Clear: Mixed Drinkware Sets 10 Oz Plastic Cups for sale eBay Keurig K Select Coffee Maker Review Consumer Reports