We are addressing incomplete participation in several ways. We are conducting a postal campaign seeking consent to collect data from health and administrative sources (described later) and inviting re-enrolment in ALSPAC by participants who have now reached the age of 18 years. We plan to extend this campaign to eligible individuals who have never previously participated. We are currently seeking support under Section 251 of the NHS Act (2006) to collect routine data on non-responders to this campaign. Through data linkage, we can increase the completeness of the study data set in participants and better characterize non-participants in order to investigate possible participation biases. Linkage offers additional benefits through providing data to inform ALSPAC’s efforts to fully trace all enrolled participants. We continue to engage the sample through new media, including a study children’s Facebook page, and through targeted community engagement and data collection. These initiatives and key ALSPAC developments are developed in consultation with cohort participants through an advisory committee (ALSPAC Teenage Advisory Panel, TAP), participant representation on the ALSPAC Ethics and Law Committee and participant focus groups.
