This is Markus Olapade, Evaluation Specialist at the International Initiative for Impact Evaluation (3ie), for which I am primarily working on the Agricultural Innovation Thematic Window. I would like to add to a point mentioned by Matthieu Stigler (Message 44) regarding results that vary across different studies and draw your attention to two important tools. If some studies show significant effects while other studies, on the same subject, don't, it becomes difficult to judge which study to believe and which not. Here Systematic Reviews and Meta-Analysis become important. A systematic review looks at all studies on a subject (published or unpublished ones) and then through a transparent selection process identifies the rigorous ones (ex-ante or ex-post designed) and synthesizes their results. Meta-analysis, in addition, takes the results from the individual studies and creates a weighted average. This provides a statistical method that allows us to interpret the existing body of evidence. More information on Meta-analysis can be availed on the website of the Cochrane Collaboration: http://www.cochrane-net.org/openlearning/html/mod12-2.htm More information on Systematic Reviews can be availed on the website of the Cambell Collaboration: http://www.campbellcollaboration.org/what_is_a_systematic_review/ Markus Olapade (Dr) Evaluation Specialist GDN-3ie Program 2nd Floor, West Wing, ISID Complex Plot No. 4, Vasant Kunj Institutional Area New Delhi 110070 India e-mail: molapade (at) 3ieimpact.org [To contribute to this conference, send your message to [log in to unmask] For further information, see http://www.fao.org/nr/research-extension-systems/res-home/news/detail/en/c/217706/ ]. ######################################################################## To unsubscribe from the Impact-L list, click the following link: https://listserv.fao.org/cgi-bin/wa?SUBED1=Impact-L&A=1