Large corporations use planning to allocate resources internally among their divisions and subsidiaries. Many modern firms also use regression analysis to measure market demand to adjust prices and to decide upon the optimal quantities of output to be supplied. Planned obsolescence is often cited as a form of economic planning that is used by large firms to increase demand for future products by deliberately limiting the operational lifespan of its products. Thus, the internal structures of corporations have been described as centralized command economies that use both planning and hierarchical organization and management.