It argues that the law of demand is the most famous law in economics and is also the truest law for many economists. One reason for this belief is that elasticities allow economists to quantify differences between markets without standardizing units of measurement (Aycock, 2010). The law of demand explains that, all else being equal, when the price of a good increases, the quantity demanded decreases and when the price of a good decreases, the quantity demanded increases. In terms of elasticity, price elasticity of demand (PED) measures consumers' sensitivity to a change in price (McConnell et al., 2015, p.134). Prices are elastic when a change in price results in a larger percentage change in the quantity demanded. For example, if the price of a Snickers bar falls by 20% but demand increases by 80%, PED = -4.0. This price change could encourage consumers to purchase alternative candy bars. Inelastic price changes result in a smaller percentage change in quantity demanded. If the price of tobacco falls by 30% but demand only increases by 10%, PED = -0.33. Since it is highly addictive and there is no substitute, if the price of cigarettes increases, smokers will likely continue to do so (Pettinger,