When economists are asked why the price of fuel fluctuates, they often explain that price changes are due to the "market"--the interaction of all of the people around the world who buy and sell crude oil and fuels in the global marketplace. These buyers and sellers decide how much oil and oil products they are willing to buy or sell at a given price. Their decisions can be affected by several factors including weather, refinery operations, and geopolitical and economic conditions. The price of other commodities, such as wheat and corn, are determined in much the same way. I touched on these points a bit in last Friday's post.