"Contract for sale" includes both a present sale of goods and a contract to sell goods at a future time. In economics, we use elasticity to measure the responsiveness of buyers and sellers relative to the change in the price of goods and services.The significant features for the year with regard to industrial out put were 1 Substantial increase in the output of durable goods. The contract demand as specified in the contract. b. The measured demand . Demand can be classified as elastic, inelastic or unitary. An elastic demand is one in which the change in quantity demanded due to a change in price is large.