The rationale is the need to identify and exploit emerging opportunities and to consolidate research efforts in order to create a critical mass of activities. Several related trade-offs are apparent: the desire to specialise versus the desire to diversify, a concern with harnessing high-technology sectors versus a concern with meeting the innovation needs of established industries, adopting a science-driven versus a market or society-driven approach, and a focus upon meeting short-term needs versus a focus upon long-term opportunities. Many formal prioritisation processes tend not to meet the often unrealistic expectations of their sponsors owing to system inertia and the medium-term commitment of most resources to existing lines of work. Countries have taken very different approaches to priority setting (Box 7.5).