Knock-to-nudge methods to improve survey participation in the UK

Relevance &amp; research question: data collection organisations are shifting toward new approaches, with social surveys undergoing significant design and implementation changes. Since the COVID-19 pandemic, agencies have increasingly moved to online data collection due to dwindling response rates and rising fieldwork costs. A key challenge for self-completion general population surveys is the absence of field interviewers to facilitate recruitment and participant retention. This research examines the UK survey landscape, aiming to identify recruitment methods for self-administered surveys, that can produce more representative samples of the general population.<br/><br/>Methods &amp; data: we present findings from an information request sent to the UK’s nine most important survey agencies. We collected information on surveys without field interviewers conducted between 2018 and early 2024, including publicly available technical and methodological reports and other survey materials, along with internal reports provided by the agencies. We processed and codified this information, building a spreadsheet containing 144 instances of 59 longitudinal and cross-sectional surveys, along with 227 communication materials. <br/><br/>Results: the responses for the surveys in our dataset use 57% online, 38% paper, and 5% telephone modes. Most surveys (84%) offer incentives to participants, with 92% being monetary and only 33% given unconditionally. Response rates vary widely – household-based cross-sectional surveys tend to have lower response rates (81% at 30% response or lower) than individual-based ones (47% at 30% or lower). Longitudinal surveys generally have the highest response rates. While only 35% of reports assess sample representativeness, the general trend confirms that mixed-mode surveys yield more representative samples than single-mode surveys.<br/><br/>Added value: to our knowledge, this review is the first coordinated effort to collate and summarise recruitment strategies for surveys without field interviewers in the UK. It covers sampling design, communication strategies and materials, incentivisation, fieldwork procedures, response rates, and report quality assessments. Our dataset provides insights into the current state of survey practice and helps identifying practices that might contribute towards higher response rates and sample representativeness.