As a rule, the wider the controls, the harder they are to enforce. In 1970 the Ghanaian government attempted to control 6,000 prices for 700 groups of products, yet its Prices and Incomes Board had only 400 personnel. The scale of such a task is beyond even the most competent agencies. Prices in such a system are often set by adding a fixed margin to costs. This removes any incentive for firms to reduce costs. Furthermore, controlled prices discourage new investment, so that as demand expands, shortages begin to appear. Often the poorest consumers, the supposed beneficiaries of price controls, suffer the consequences along with others.