Experimental evidence on response rates and data measurement in phone versus online surveys

Researchers and policymakers face substantial challenges in selecting methods for conducting remote surveys, particularly when collecting sensitive information, reaching hard-to-access populations, during emergencies, or working in vulnerable contexts. This study provides experimental evidence on the relative effectiveness of two remote survey methods: enumerator-led phone surveys and self-administered online surveys. In a randomized trial in El Salvador, we find that respondents assigned to phone surveys were, on average, 42 percentage points more likely to complete the survey, with particularly higher completion rates among women and older adults. Phone surveys reduced careless responses and decreased the likelihood of respondents reporting high parental stress. Regarding cost-effectiveness, although the direct cost of implementing phone surveys is higher than that of online surveys, the observed differences in response rates indicate that the cost per completed interview can be lower for phone when outreach is costly.