Melitz, Marc J.Magnuson, Alex2026-06-0920262026-05-132026Magnuson, Alex. 2026. Topics In International Trade and Migration. Doctoral Dissertation, Harvard University Graduate School of Arts and Sciences.32701415https://p2p8-sa-zuvru-a9vusux.re-cotta.com/handle/1/42740371This dissertation comprises three essays on firm uncertainty, data investment, and political responses to migration. The first chapter examines the political backlash triggered by the 2015 European refugee crisis. Using a shift-share instrument that exploits pre-crisis asylum seeker nation- ality compositions to predict differential exposure across European countries, I estimate the causal effect of refugee inflows on migration policy restrictiveness. Crisis exposure gen- erated a significant tightening of migration policy, concentrated in border control and en- forcement rather than legal migration channels. A bystander analysis reveals that even countries with minimal direct exposure tightened policy, suggesting contagion effects that operate through political rather than demographic channels. The second and third chapters develop a unified framework for understanding how firms use data to resolve operational uncertainty. The second chapter documents that larger firms produce more accurate revenue forecasts, decomposes this advantage into ac- tionable and non-actionable channels using revenue volatility controls, and calibrates a structural model revealing the operational execution channel as the primary driver. A counterfactual exercise shows that improvements in data technology are progressive, dis- proportionately benefiting smaller firms. The third chapter extends this framework to international trade, introducing active data investment as a choice variable and exploiting a novel matched employer-employee dataset linking French administrative records to firm-level data hiring. Data investment predicts both entry into and survival in foreign markets.application/pdfenBig DataInternational TradeMigrationRefugeesEconomicsThesis or Dissertation2026-06-090009-0008-2080-7895