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Impacts on Information Networks A Randomized Controlled Test of Strategic Network Change

Impacts on Information Networks A Randomized Controlled Test of Strategic Network Change Scott McNiven • UC Davis PacDev March 17, 2012. Motivation. The big picture: The diffusion of innovations drives economic growth.

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Impacts on Information Networks A Randomized Controlled Test of Strategic Network Change

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  1. Impacts on Information Networks A Randomized Controlled Test of Strategic Network Change Scott McNiven • UC Davis PacDev March 17, 2012

  2. Motivation • The big picture: • The diffusion of innovations drives economic growth. • The rural poor face pervasive market failures. Networks may substitute for formal markets. • Strategic network formation models look at it “from the ground up”. • Such models do not directly address changes in existing networks due to policy shocks. • My results concern “strategic network change”. • 3. Find policy instruments that promote technology diffusion.

  3. Intro The Introduced Agricultural Technology:Orange-Fleshed Sweet Potato (OSP) • All sweet potatoes in Uganda: • Vine-propagated • Vines are given, not sold, to other farmers • Two seasons per year • Primarily-subsistence staple crop • Traditional varieties: • Little or no vitamin A • White or yellow • 75% cultivating at baseline • OSP: • Vitamin A dense • Orange • Bred in Uganda, not a GMO • <0.5% cultivating at baseline • Higher yielding • Dries out more easily in dry season or in sun • Rots more easily when left in the ground past maturity

  4. Intro The HarvestPlus Program • Cluster-randomized controlled trial • In Central and Eastern Uganda • From August 2007 to June 2009 The goal: • Fight vitamin A deficiency The treatment: • 20 kg of OSP vines (enough to plant 1/4 acre) • Trainings on OSP cultivation, cooking, nutrition, and marketing. Kampala

  5. Intro Sample and Research Design Farmer Group Members 14 sampled per community Nonmembers 5 sampled per community All farmer group (FG) members in treated Communities were treated Nonmembers (NM) in treated Communities 48 Treated Communities No farmer group (FG) members in control Communities were treated 36 Control Communities NM in control communities

  6. Intro Motivation:Document “strategic network change” (not formation) • Two types of policies: • Policies that “assign” links. E.g., roommates or to classrooms. • What is the impact of network tie assignment on node characteristics? • Policies that change agents’ characteristics but do not directly manipulate social relations. • What is the impact of the assignment of a characteristic to nodes on network ties? • How might networks change under the policy? • We expect agents to make ties to treated agents. • Untreated agents might break ties to other untreated agents if there are costs to maintaining ties. • Do new links become more likely to form? • Do existing links become more likely to be retained?

  7. Network tie definition: Information neighbor • Survey question: • In the 12 months before the baseline, have you or anyone else in your household had a conversation about farming or health with someone in [other HH]? • If the respondent answers “Yes” with respect to the [other HH], then it is an “information neighbor” to the respondent’s HH. • When I say “link” or “tie” I’m referring to an “information neighbor link”. • Links are “directed” – HH “A” may be a neighbor of “B” without “B” being a neighbor of “A”.

  8. Intro Three channels of peer-to-peer diffusion: Do technologies diffuse through new links in addition to existing links? • Solid white lines indicate links between agents. • A and B are offered a technology. • “D” might acquire the technology: • Directly through an existing link: B  D • Directly through a new link (dashed white line): A  D • Indirectly: A  C  D A C 3. 2. 1. B D

  9. Econometric Specification

  10. FG and NM gain FG neighbors

  11. A few FG members gained many NM neighbors Treated Control

  12. New links are formed; smaller effects on old links

  13. Surprisingly, no direct association with OSP Cultivation in the Fourth Season

  14. Households adding adopting (fewer non-adopting) ties were more likely to cultivate OSP in the Fourth Season

  15. In Summary • Increased ties among farmer group members and between members and nonmembers • Consistent with strategic network formation models • Significant “churn” in nonmember-nonmember links and conversations • Nonmembers face incentives form new links to other nonmembers. • Suggests that links are costly to maintain. • A few farmer group members began talking with many nonmembers. • Some individuals may be “central” to diffusion. • Households adding adopting (fewer non-adopting) ties were more likely to cultivate OSP in the Fourth Season • New links are associated with diffusion. Are they causal?

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