<P> Approximate estimates of the cross price elasticities of preference - independent bundles of goods (e.g. food and education, healthcare and clothing, etc .) can be calculated from the income elasticities of demand and market shares of individual bundles, using established models of demand based on a differential approach . </P> <P> Below are some examples of the cross-price elasticity of demand (XED) for various goods: </P> <Table> <Tr> <Th> Good </Th> <Th> Good with Price Change </Th> <Th> XED </Th> </Tr> <Tr> <Td> Butter </Td> <Td> Margarine </Td> <Td> + 0.81 </Td> </Tr> <Tr> <Td> Beef </Td> <Td> Pork </Td> <Td> + 0.28 </Td> </Tr> <Tr> <Td> Entertainment </Td> <Td> Food </Td> <Td> - 0.72 </Td> </Tr> </Table> <Tr> <Th> Good </Th> <Th> Good with Price Change </Th> <Th> XED </Th> </Tr>

Who gave the concept of cross elasticity of demand