The "soda tax" is unlikely to make Mexicans lighter : new evidence on biases in elasticities of demand for soda

Mexico's 'soda tax' has been predicted to reduce average weights by two to four pounds, based on extant estimates of an own-price elasticity of quantity demand for soda of between -1.0 and -1.3. These estimates ignore consumer responses on the quality margin and correlated measurement errors. We use Mexican household budget survey data and city-level soda prices to estimate unrestricted demand models that correct for both errors. The corrected own-price elasticity of quantity demand is just -0.2 to -0.3, so tax-induced soda price increases might cut average weights by less than one pound, which is too small to improve health.