Linkages between surveys and administrative data provide an important opportunity for social and health research, but such linkages often require the informed consent of respondents. We use experimental data collection across five different samples to study how consent decisions are made. More reflective decision processes are associated with higher rates of consent, greater comprehension of the proposed data linkage, and greater confidence in the decision, but only about a third of respondents report using a reflective decision process. This suggests that the provision of additional information is unlikely to lead to significant improvements in informed consent.
