The market for manufactured goods is what economists call 'imperfect,' because each company has its own style, its own reputation, and its own locations and all of the arts of advertisement and salesmanship are devoted to making it even more imperfect by attracting buyers to particular brand names. Even small businesses that depend upon outside channels of retail distribution may have the final say in what prices they will charge, and great corporations can differentiate their goods in order to create demand of them. In this type of market, supply normally is very elastic--that is responsive to demand--in the short run. Stocks or inventories are held at some point in the chain of distribution while stocks are running down or building up, there is time to change the level of production, and once a price has been set, it is rarely altered in response to moderate changes in demand. Even in a deep slump, defensive rings may be formed to prevent price cutting. In the long run, as well as in the short, supply is responsive to demand in the market for manufactures. It is easier to change the composition of a firm's output than it is to change the production of a mine or a plantation. And when changes in demand are not too rapid, gross profits from one plant can be siphoned off and invested in something quite different. When business is good, moreover, there is continual new investment so that productive capacity is adapted to meeting changing requirements. Workers themselves may not even be aware of changes in the final commodities to which their work contributes, and the level of wages for any grade of factory labour is very little affected by the fortunes of a particular market. The 'imperfection' of the market for manufactured goods is reflected in all of the following aspects, except ______.