The second major design decision is a decision in principle on the geographical scope of the project: how many countries and which ones; how many sites per country; ecosystem parameters, and duration. Selection of too few countries or sites could lead to lightweight recommendations and the possibility that findings are unrepresentative. The impact on the overall project should any one country or institution fail to deliver is proportionately high. On the other hand, selection of too many sites would spread the risks, but incur the dangers of managerial complexity and unnecessary replication of findings. Much depends on the capability and financial resources of the sponsoring institution, but it is tentatively suggested that an upper limit of practicality for a single comparative project might be 15-20 countries and three to five selected representative sites per country, and a lower limit might be five countries with two sites per country. It is better to do fewer studies well than many superficially.