Research

Abstract

I exploit the staggered introduction of 3G mobile Internet technology across South Africa to estimate its impact on political participation, electoral competition, voters’ preferences, and protests. Combining granular coverage data with administrative records on municipal elections, I show that in 2016 mobile Internet availability caused a 2-percentage-point increase in voter turnout and a 3-percentage-point reduction in the vote share of the ruling party. The main opponents gained from mobile Internet arrival. The number of parties running for election and the number of protests grew. I provide suggestive evidence that both information and coordination mechanisms could explain the observed results.

Abstract

Asymmetric information can distort market outcomes. I study how the online disclosure of information affects consumers’ behavior and firms’ incentives to upgrade product quality in markets where information is traditionally limited. I first build a model of consumer search with firms’ endogenous quality decisions. In this model, lower search costs reallocate demand toward higher-quality producers, raising firms’ incentives to upgrade quality, and more so for firms selling ex-ante lower-quality products. I then use the access to online reviews to proxy for reductions in consumers’ search costs and estimate its impact on the restaurant industry in Rome, exploiting the abolition of mobile roaming charges in the EU in 2017 for identification. Based on a unique dataset combining monthly information from Tripadvisor with administrative social-security records, I find that, after the policy, revenues and total employment in mid- and high-rating restaurants grow by 3-10%. In turn, the probability for low-rating restaurants to exit the market doubles compared to the pre-policy period, while surviving low- and mid-rating establishments hire workers with higher wages and better curricula, eventually improving their Tripadvisor ratings. Overall, the share of low-rating restaurants in the most tourist areas decreases by 2.5 pp. My findings have implications for the role of review platforms in the performance of offline industries under asymmetric information.

Abstract

Social media campaigns are increasingly used for public health objectives, yet their effectiveness remains poorly understood. This paper presents results of two trials evaluating the impact of a large malaria prevention Facebook campaign in India, 1-to-4 months after ad exposure. The first is a cluster randomized controlled trial that evaluated a “real world” ad campaign, where experimental groups were assigned at the district level and survey respondents were independently recruited in three high-burden states. While this intervention increased the use of bed nets among individuals living in solid (concrete) houses by 10%, the campaign was ineffective for those living in non-solid dwellings, where malaria risk is higher. In turn, self-reported malaria incidence decreased by 39% among individuals living in solid houses. Consistently, administrative health facility data show a reduction in urban monthly incidence rates by 37%, but no effect in rural areas. Did the ad campaign not persuade households at greater malaria risk or did it fail to reach them? In a second field experiment we varied exposure to the same ads at the individual level, using the re-marketing tools of the ad platform. We find that bed net use increased for both types of households, suggesting that social media campaigns need to refine their targeting strategies to reach development objectives. The paper concludes proposing a series of micro-targeting approaches to maximize impacts in sub-populations of interest.

Abstract

We conducted a field experiment on Facebook Messenger to evaluate the effectiveness of two social marketing video series at reshaping gender norms and reducing social acceptability of violence against women in India. To test different formats, we randomly invited participants to watch either a humorous fictitious drama (implicit format) or a documentary with clear calls to action (explicit format), or a placebo series (control). Our results show that the fictitious drama was more successful in facilitating attitudinal change, reducing the acceptability of regressive gender norms and violence against women by respectively 0.20 and 0.17 standard deviations. In contrast, the documentary was more effective in encouraging behavioral change, influencing the willingness to share the videos and promoting information-seeking behaviors. Moreover, in the medium term, documentary viewers were 91% more likely to add a frame anti-violence against women to their Facebook profile picture, a public commitment to social action. The absence of heterogeneous effects across socioeconomic indicators suggests that social media could be a viable platform for conveying social marketing campaigns to marginalized communities.

Abstract

How does the internet affect young people's mental health? We study this question in the context of Italy using administrative data on the universe of cases of mental disorders diagnosed in Italian hospitals between 2001 and 2013, which we combine with information on the availability of high-speed internet at the municipal level. Our identification strategy exploits differences in the proximity of municipalities to the pre-existing voice telecommunication infrastructure, which was previously irrelevant but became salient after the advent of the internet. We find that access to high-speed internet has a harmful effect on mental health for young cohorts but not for older ones. In particular, internet access is associated with an increase in diagnoses of depression, anxiety, drug abuse, and personality disorders-- for both males and females - and of eating and sleep disorders - for females only. We find similar results for urgent and compulsory hospitalizations and self-harm episodes. These results suggest that the effect of broadband is driven by a rise in the underlying prevalence of mental disorders and not merely by increased awareness about these pathologies.

Abstract

Virtual Lab is an open-source set of tools for online recruitment, intervention, and surveying via digital advertising and social-media platforms. It was built specifically for researchers and policymakers. It can be used to perform impact evaluations, inform the targeting of large-scale digital ad campaigns, collect and visualize cross-sectional survey data in real time, or build high-frequency longitudinal panel surveys. This manual provides an introduction to the survey theory underpinning Virtual Lab, lays out detailed guidelines for designing online studies within the platform, shares costs data and lessons learned from recent trials, and lays out promising areas for future research. Virtual Lab can be self-hosted on private or public cloud infrastructure. All code is open source. Further details about this platform, including the code to independently run it, can be found at https://vlab.digital.