We identify earnings impacts of exposure to an infant health intervention in Sweden, using individual linked administrative data to trace potential mechanisms. Leveraging quasi-random variation in eligibility, we estimate that exposure was associated with higher test scores in primary school for...

Twin births are often construed as a natural experiment in the social and natural sciences on the premise that their occurrence is quasi-random. We present new population-level evidence challenging this premise. Using data on about 18 million births in 72 countries, we find that maternal...

Twin births are often construed as a natural experiment in the social and natural sciences on the premise that the occurrence of twins is quasi-random. We present new population-level evidence that challenges this premise. Using individual data for more than 18 million births (more than 500,000...