Household surveys are one of the primary methodological tools employed in global health research. In this paper, I try to gain insight into the production of global health knowledge by elaborating upon the process of data collection for such surveys. I do so by narrating a story of an impact evaluation in northern India, drawing attention to how data collectors, called ‘enumerators’, follow or disregard different aspects of the research protocol while conducting survey interviews. I pay close attention to how enumerators translate and ask questions, and how the ethical challenges they face affect their interactions with respondents. I use this analysis to draw parallels between the work of enumerators and global health researchers. I argue that researchers also acknowledge or ‘unknow’ different aspects of research practice in order to produce scientific evidence and claim expertise.