In his comprehensive review of the empirical evidence, Kling similarly concluded that there was little real impact on middle managers, or supervisors for that matter. Indeed, rather than supplanting managerial decision-making, he contends that computer-generated analysis was often used as a tool to justify decisions that senior administrators had planned to make in any case. The new technology can create competitive advantage by giving firms new ways to outperform their rivals. Organisations can do this in at least three ways: by reducing product or service cost; by enhancing product or service differentiation; and by changing competitive scope. Many of the developments discussed in this book have major implications for organisation structure. The problem is that there is little consensus on which of these implications will materialise, and within what time-frame. A product hierarchy reduces costs of coordination by breaking the total organisation according to product/service produced or geographic region, and providing each unit with all necessary resources.