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Credible evidence on complex change processes: key challenges in impact evaluation on agricultural value chains


  • Ton, Giel
  • Vellema, Sietze
  • DeRuyterDeWildt, Marieke


Although a growing field of policy intervention, the effectiveness of public-private value chain support is regularly questioned in the policy realm. Partly resulting from stronger pressures on aid money to show its worth, convincing evidence is asked for the effect on poverty alleviation. However, impact evaluations of interventions are challenging: outcome indicators are often multi-dimensional, impact is generated in dynamic and open systems and the external validity of conclusions are often limited, due to contextual particularities. Therefore, there is a strong case for theory-based evaluation where logic models indicate how the intervention is expected to influence the incentives for people’s behaviour. The key assumptions inherent in these casual models can be tested through observation and measurement of specific outcome indicators, using mixed methods in triangulation. The mix of methods will have to anticipate the major threats to validity to the type of evaluative conclusion that the evaluation is expected to generate .Following the work of Shadish, Cook and Campbell (2002), validity threats relate to: 1) statistical conclusion validity; 2) internal validity; 3) construct validity; and, 4) external validity. The authors propose the combined use of data-set observations and causal-process observations in a comparative case-study design, based on critical realist concept of contextmechanism-outcome configurations. The use of a realist method to describe and analyze intervention pilots, facilitates the exchange of experiences between development agencies with evidence-based research. Its defined generalisation domain may prevent uncritical embracement of good practices. Certain value chain upgrading strategies may be viable and effective in a range of situations but are not the panacea, the standard solution, for creating market access; they all involve specific institutional arrangements that ‘fire’ specific mechanisms and incentives that depend on the institutional environment and social capital of stakeholders involved.

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  • Ton, Giel & Vellema, Sietze & DeRuyterDeWildt, Marieke, 2011. "Credible evidence on complex change processes: key challenges in impact evaluation on agricultural value chains," MPRA Paper 32027, University Library of Munich, Germany.
  • Handle: RePEc:pra:mprapa:32027

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    References listed on IDEAS

    1. Cook, Michael L., 1994. "The Role of Management Behavior in Agricultural Cooperatives," Journal of Agricultural Cooperation, National Council of Farmer Cooperatives, vol. 9.
    2. Duflo, Esther & Glennerster, Rachel & Kremer, Michael, 2008. "Using Randomization in Development Economics Research: A Toolkit," Handbook of Development Economics, Elsevier.
    3. Patricia Rogers, 2009. "Matching impact evaluation design to the nature of the intervention and the purpose of the evaluation," Journal of Development Effectiveness, Taylor & Francis Journals, vol. 1(3), pages 217-226.
    4. Ravallion Martin, 2009. "Should the Randomistas Rule?," The Economists' Voice, De Gruyter, vol. 6(2), pages 1-5, February.
    5. Norman Blaikie, 1991. "A critique of the use of triangulation in social research," Quality & Quantity: International Journal of Methodology, Springer, vol. 25(2), pages 115-136, May.
    6. Maredia, Mywish K., 2009. "Improving the proof: Evolution of and emerging trends in impact assessment methods and approaches in agricultural development," IFPRI discussion papers 929, International Food Policy Research Institute (IFPRI).
    7. Ton, Giel, 2008. "Challenges for smallholder market access: a review of literature on institutional arrangements in collective marketing," MPRA Paper 33329, University Library of Munich, Germany.
    8. Ragin, Charles C., 2000. "Fuzzy-Set Social Science," University of Chicago Press Economics Books, University of Chicago Press, edition 1, number 9780226702773, July.
    9. Borgen, Svein Ole, 2004. "Rethinking incentive problems in cooperative organizations," Journal of Behavioral and Experimental Economics (formerly The Journal of Socio-Economics), Elsevier, vol. 33(4), pages 383-393, September.
    10. Chris Cornforth, 2004. "The Governance of cooperatives and mutual associations: a paradox perspective," Annals of Public and Cooperative Economics, Wiley Blackwell, vol. 75(1), pages 11-32, March.
    11. Chiu, Yung-ho & Huang, Chin-wei & Ma, Chun-Mei, 2011. "Assessment of China transit and economic efficiencies in a modified value-chains DEA model," European Journal of Operational Research, Elsevier, vol. 209(2), pages 95-103, March.
    12. repec:ucp:bkecon:9780226702766 is not listed on IDEAS
    13. Tony Lawson, 2009. "Applied economics, contrast explanation and asymmetric information," Cambridge Journal of Economics, Oxford University Press, vol. 33(3), pages 405-419, May.
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    More about this item


    rural development; mixed methods; attribution; organisational performance; realist evaluation;

    JEL classification:

    • D23 - Microeconomics - - Production and Organizations - - - Organizational Behavior; Transaction Costs; Property Rights
    • A12 - General Economics and Teaching - - General Economics - - - Relation of Economics to Other Disciplines
    • O12 - Economic Development, Innovation, Technological Change, and Growth - - Economic Development - - - Microeconomic Analyses of Economic Development

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