The four commodities mentioned in this article, crude oil, heating oil, gasoline and natural gas are all substitutes for one another. This is true because the cross elasticity of demand states that as the percentage change in the quantity demanded of one commodity results from a one percent change in the price of another commodity. In other words, the increase in demand for crude oil, gasoline, and heating oil was the outcome of the price increase in natural gas. As the price of natural increases, the quantity demanded for the three other energy commodities increase. The market system today functions on price.
Consumers make their decision on what to buy by the price of their desired good.
Naturally, consumers will choose the lower price of a commodity they wish to purchase. The commodity, energy, is something that people can not go without during the winter months. If their is a shortage, which means that consumers demand more than the available supply, it leads to an increase in price. As shown in the graph below, as the supply decreases, the price increases. This means that the price is inelastic.