In this issue we feature 8 current papers on the theme of social capital, chosen by Fabio Sabatini (Università degli Studi di Roma “La Sapienza”):

1. Social Networks, Confirmation Bias and Shock Elections Gallo, E.; Langtry, A.

2. Does Scarcity Reduce Cooperation? Experimental Evidence from Rural Tanzania Gustav Agneman; Paolo Falco; Exaud Joel; Onesmo Selejio

3. Social Media and Political Contributions: The Impact of New Technology on Political Competition Maria Petrova; Ananya Sen; Pinar Yildirim

4. Contact vs. Information: What shapes attitudes towards immigration? Evidence from an experiment in schools Florio, Erminia

5. School Friendship Networks, Homophily and Multiculturalism: Evidence from European Countries Campigotto, Nicola; Rapallini, Chiara; Rustichini, Aldo

6. Family Ties and Child Obesity in Italy Federico Crudu; Laura Neri; Silvia Tiezzi

7. Inequality, Institutions and Cooperation Markussen, Thomas; Sharma, Smriti; Singhal, Saurabh; Tarp, Finn

8. Mothers' Social Networks and Socioeconomic Gradients of Isolation Alison Andrew; Orazio P. Attanasio; Britta Augsburg; Jere Behrman; Monimalika Day; Pamela Jervis; Costas Meghir; Angus Phimister

1. Social Networks, Confirmation Bias and Shock Elections Gallo, E.; Langtry, A.

In recent years online social networks have become increasingly prominent in political campaigns and, concurrently, several countries have experienced shock election outcomes. This paper proposes a model that links these two phenomena. In our set-up, the process of learning from others on a network is influenced by confirmation bias, i.e. the tendency to ignore contrary evidence and interpret it as consistent with one's own belief. When agents pay enough attention to themselves, confirmation bias leads to slower learning in any symmetric network, and it increases polarization in society. We identify a subset of agents that become more/less influential with confirmation bias. The socially optimal network structure depends critically on the information available to the social planner. When she cannot observe agents' beliefs, the optimal network is symmetric, vertex-transitive and has no self-loops. We explore the implications of these results for electoral outcomes and media markets. Confirmation bias increases the likelihood of shock elections, and it pushes fringe media to take a more extreme ideology. JEL: C63 D72 D83 D85 D91 L15 Keywords: social learning, confirmation bias, network, elections, media Date: 2020–11–02 URL: http://d.repec.org/n?u=RePEc:cam:camdae:2099&r=soc

2. Does Scarcity Reduce Cooperation? Experimental Evidence from Rural Tanzania Gustav Agneman (DERG, Department of Economics, University of Copenhagen); Paolo Falco (DERG, Department of Economics, University of Copenhagen); Exaud Joel (Department of Economics, University of Dar Es Salaam); Onesmo Selejio (Department of Economics, University of Dar Es Salaam)

Cooperation is essential to reap efficiency gains from specialization, not least in poor communities where economic transactions often are informal. Yet, cooperation might be more difficult to sustain under scarcity, since defecting from a cooperative equilibrium can yield safe, short-run benefits. In this study, we investigate how scarcity affects cooperation by leveraging exogenous variation in economic conditions induced by the Msimu harvest in rural Tanzania. We document significant changes in food consumption between the pre- and post-harvest period, and show that lean season scarcity reduces socially efficient but personally risky investments in a framed Investment Game. This can contribute to what is commonly referred to as a behavioral poverty trap. JEL: C71 C93 D91 Keywords: scarcity, cooperation, field experiment Date: 2020–02–11 URL: http://d.repec.org/n?u=RePEc:kud:kuderg:2004&r=soc

3. Social Media and Political Contributions: The Impact of New Technology on Political Competition Maria Petrova; Ananya Sen; Pinar Yildirim

Political campaigns are among the most sophisticated marketing exercises in the United States. As part of their marketing communication strategy, an increasing number of politicians adopt social media to inform their constituencies. This study documents the returns from adopting a new technology, namely Twitter, for politicians running for Congress by focusing on the change in campaign contributions received. We compare weekly donations received just before and just after a politician opens a Twitter account in regions with high and low levels of Twitter penetration, controlling for politician-month fixed effects. Specifically, over the course of a political campaign, we estimate that the differential effect of opening a Twitter account in regions with high vs low levels of Twitter penetration amounts to an increase of 0.7-2% in donations for all politicians and 1-3.1% for new politicians, who were never elected to the Congress before. In contrast, the effect of joining Twitter for experienced politicians remains negligibly small. We find some evidence consistent with the explanation that the effect is driven by new information about the candidates, e.g., the effect is primarily driven by new donors rather than past donors, by candidates without Facebook accounts and tweeting more informatively. Overall, our findings imply that social media can intensify political competition by lowering costs of disseminating information for new entrants to their constituents and thus may reduce the barriers to enter politics. Date: 2020–11 URL: http://d.repec.org/n?u=RePEc:arx:papers:2011.02924&r=soc

4. Contact vs. Information: What shapes attitudes towards immigration? Evidence from an experiment in schools Florio, Erminia

We analyze whether (correct) information provision on immigration is more effective than contact in shaping attitudes towards immigration. We collect data from a randomized experiment in 18 middle- and high-school classes in the city of Rome. Half of the classes meet a refugee from Mauritania, whereas the rest of them attend a lecture on figures and numbers on immigration in Italy and the world. On average, students develop better attitudes towards immigration (especially in the case of policy preferences and the perceived number of immigrants in their country) after the information treatment more than they do after the contact treatment, whereas neither treatment affects feelings associated to immigrants. Also, students having received the information treatment strongly adjust their knowledge on immigration. However, students' individual characteristics and school type (i.e. middle vs. high school) affect treatments' effectiveness. JEL: C93 J15 Z1 Z13 Keywords: Attitudes towards immigration,Information Provision,Contact Theory,Randomized Experiment Date: 2020 URL: http://d.repec.org/n?u=RePEc:zbw:glodps:699&r=soc

5. School Friendship Networks, Homophily and Multiculturalism: Evidence from European Countries Campigotto, Nicola; Rapallini, Chiara; Rustichini, Aldo

This paper investigates the determinants of school friendship networks among adolescents, proposing a model of network formation and estimating it using a sample (CILS4EU) of about 10,000 secondary school students in four countries: England, Germany, the Netherlands and Sweden. We test the idea that networks arise according to homophily along many characteristics (gender, school achievement and ethnic and cultural backgrounds), and assess the relative importance of each factor. In addition to gender, we find that country of origin, generational status and religion predict friendship for foreign-born students. For country-born individuals, ties depend on a broader set of factors, including socioeconomic status and school achievement. In sum, homophilic preferences go considerably beyond ethnicity. Multiculturalism, which gives prominence to ethnic backgrounds, risks emphasising the differences in that dimension at the expense of affinity in others. JEL: D85 J15 Z13 Keywords: Friendship,Homophily,Immigration,Networks,Social cohesion Date: 2020 URL: http://d.repec.org/n?u=RePEc:zbw:glodps:695&r=soc

6. Family Ties and Child Obesity in Italy Federico Crudu; Laura Neri; Silvia Tiezzi

This paper examines the impact of overweight family members on weight outcomes of Italian children aged 6 to 14 years. We use an original dataset matching the 2012 cross sections of the Italian Multipurpose Household Survey and the House hold Budget Survey. Since the identification of within-family peer effects is known to be challenging, we implement our analysis on a partially identified model using inferential procedures recently introduced in the literature and based on standard Bayesian computation methods. We find evidence of a strong, positive effect of both overweight peer children in the family and of overweight adults on children weight outcomes. The impact of overweight peer children in the household is larger than the impact of adults. In particular, the estimated confidence sets associated to the peer children variable is positive with upper bound around one or larger, while the confidence sets for the parameter associated to obese adults often include zero and have upper bound that rarely is larger than one. JEL: I12 C15 C21 C35 Keywords: child obesity; confidence sets; partial identification; peer effects within the family Date: 2020–10 URL: http://d.repec.org/n?u=RePEc:usi:wpaper:845&r=soc

7. Inequality, Institutions and Cooperation Markussen, Thomas (University of Copenhagen); Sharma, Smriti (Newcastle University); Singhal, Saurabh (Lancaster University); Tarp, Finn (University of Copenhagen)

We examine the effects of randomly introduced economic inequality on voluntary co- operation and whether this relationship is influenced by the quality of local institutions, as proxied by corruption. We use representative data from a large-scale lab-in-the-field public goods experiment with over 1,300 participants across rural Vietnam. Our results show that inequality adversely affects aggregate contributions, and this is on account of high endowment individuals contributing a significantly smaller share than those with low endowments. This negative effect of inequality on cooperation is exacerbated in high corruption environments. We find that corruption leads to more pessimistic beliefs about others' contributions in heterogeneous groups, and this is an important mechanism explaining our results. In doing so, we highlight the indirect costs of corruption that are understudied in the literature. These findings have implications for public policies aimed at resolving local collective action problems. JEL: H41 D73 D90 O12 Keywords: inequality, institutions, corruption, public goods, lab-in-field experiment Date: 2020–10 URL: http://d.repec.org/n?u=RePEc:iza:izadps:dp13812&r=soc

8. Mothers' Social Networks and Socioeconomic Gradients of Isolation Alison Andrew (Institute for Fiscal Studies, University College London); Orazio P. Attanasio (Cowles Foundation, Yale University); Britta Augsburg (Institute for Fiscal Studies); Jere Behrman (University of Pennsylvania); Monimalika Day (Ambedkar University); Pamela Jervis (University of Chile); Costas Meghir (Cowles Foundation, Yale University); Angus Phimister (Institute for Fiscal Studies, University College London) Social connections are fundamental to human wellbeing. This paper examines the social networks of young married women in rural Odisha, India. This is a group, for whom highly-gendered norms around marriage, mobility, and work are likely to shape opportunities to form and maintain meaningful ties with other women. We track the social networks of 2,170 mothers over four years, and ï¬ nd a high degree of isolation. Wealthier women and women more-advantaged castes have smaller social networks than their less-advantaged peers. These gradients are primarily driven by the fact that more-advantaged women are less likely to know other women within their same socioeconomic group than are less-advantaged women are. There exists strong homophily by socioeconomic status that is symmetric across socioeconomic groups. Mediation analysis shows that SES differences in social isolation are strongly associated to caste, ownership of toilets and distance. Further research should investigate the formation and role of female networks. Date: 2020–11 URL: http://d.repec.org/n?u=RePEc:cwl:cwldpp:2261&r=soc

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