2 Methods and data sources

• This book applies a unique, structured, systems methodology for characterizing and grouping large populations of farm households with broadly similar livelihood, production and consumption patterns, and for whom similar development strategies would be appropriate. • As a result African households across the continent are grouped into 15 major farming systems and 58 subsystems. • The farming systems analysis integrates an extensive range of spatial data, administrative statistics, assessment reports and expert knowledge, in order to update the African component of the 2001 FAO/World Bank farming systems analysis. • Pattern recognition is key to teasing out the diversity inherent in African agriculture and in understanding common livelihood patterns (derived from crops, trees, livestock, fish and off-farm income), constraints and opportunities which define each farming system. • The principle of central tendency is used to identify the core length of growing period and travel time to the nearest market town, which are two key indicators of access to agricultural resources and access to agricultural services, respectively, that shape livelihood patterns in each farming system. • The method allows farming system drivers, trends and strategic interventions to be identified for policymakers, investors and research planners, using a synthesis of UN statistics, assessment reports and expert knowledge.