Increasing demands by government for “evidence-led” policy raise the risk that research evidence will mislead government rather than leading to an unbiased conclusion. The need for unbiased research conclusions has never been greater, yet few consumers of research understand the statistical biases with which science must always struggle. This article introduces the volume's discussion of those issues with an explanation of the major threats of bias in social science research and a map of the differing scientific opinions on how to deal with those threats. The thesis of the volume is that many of these threats could be reduced by making social science more experimental. The fact that even experimental evidence contains threats of bias does not alter that claim but merely suggests another: that educated consumers of social science may be the best defense against misleading evidence of all kinds.