This is 18 percentage points less than male-headed households. Given women’s high participation in agriculture and low access to extension, improving their access to knowledge and information on agricultural technologies may lift one of the barriers to women’s economic empowerment in Ethiopia.

Studies evaluating the impact of extension have usually involved estimating the rate of returns to extension in an agricultural production function. Returns are generally positive but vary widely across studies and contexts (Anderson & Feder, 2007; Birkhaeuser _et al._ , 1991; Evenson, 2001). Challenges in identifying a causal relationship between extension and productivity or income include endogeneity in program placement and participation, lack of baseline data, and the severity of measurement errors in key outcomes (Aker 2011; Davis, 2008). Longitudinal data with valid counterfactuals are rare and experimental evidence on the impact of intensified extension services is very scarce, especially in Sub-Saharan Africa.

Traditional models of agricultural extension were usually government-driven and involved extension agents visiting farmers to deliver knowledge and information. Owens _et al_ (2003) use panel data from a sample of resettled households in Zimbabwe to measure the impact of farmer contact with agricultural extension services. Controlling for farmer’s ability, they find that receiving one or two visits per year has a significant positive impact on crop production but the effect is highly variable across years. A similar approach is used to measure the impact of access to extension services in Côte d’Ivoire, showing positive impacts on yields for food crops, but not for cash crops (Romani, 2003).

One of the most widely used models is the Training and Visit system (T&V), which involves regular visits by extension agents to contact farmers who are expected to disseminate the information learned to other farmers in their community (Anderson _et al_ , 2005). An early study of the impact of the Kenya T&V extension system found high returns to extension (Bidlinsh and Evenson, 1993). However, these results were controversial, as a later study that revisited some of the data issues could not establish a significant impact on farmer efficiency or farm productivity (Gautam and Anderson, 1999). Gautam (2000) argues that the system was not efficacious because its approach did not focus on farmer empowerment, and was too supply-driven. In another study in Ghana, farmers were randomly selected into early and late treatment groups, to benefit from a business and technical training and input provision program (Agyei-Holmes _et al,_ 2011). The program did not show significant impacts on crop yields and incomes. However, the sample size may have been too small to detect an effect and the phased-in design did not allow for medium term measurement of impact.

To overcome weaknesses of traditional extension systems, both the content and the mode of diffusion of the information can be altered. Adopting more demand-driven and participatory approaches can help increase the relevance of the extension services to the needs of farmers, and thus promote adoption of technology. In Uganda, a public-private extension service delivery approach, in which farmer groups contracted service providers to deliver advisory services, was evaluated using post-program cross-sectional data (Benin _et al,_ 2007). The study finds that the program promoted adoption and use of agricultural production technologies but no significant impact on yield growth. Pamuk _et al_ (2014) investigate the impact of a decentralized approach to the promotion of agricultural innovation, based on local participatory innovation platforms, where 3