The use of Big Data presents numerous challenges to researchers and their projects. Josh Cowls is working at the Oxford Internet Institute and he tries to develop a greater understanding of the impact of new technology on society, democracy and everyday life. In this interview we talk about three challenges of using Big Data for valid research – epistemological, methodological and political. Is there a shift from causal to correlational research? What methods can be used to deal with different forms of data? And who creates the data, and who is affected by its use?