The emergence of sensors in mobile devices has widened the potential types of data that can be collected in official statistics. Integrating new and existing sources of data about persons and household bring new challenges. Actively combining traditional forms of data with new forms of data may give the best of both worlds in terms of data quality, representation, coherence and control. But how to design hybrid forms of data collection? In this paper, we discuss smart survey design at the hand of the four ESSnet Smart Surveys case studies: consumption, time use, physical activity and living conditions.