Data Access Groups, commonly called DAGs, are REDCap structures that restrict users to viewing records assigned to their group. They are especially important in multisite studies where staff at one site should not access records from another site. DAGs support confidentiality, site accountability, and operational control.
Consider a cohort study conducted in hospitals in Kisumu, Nairobi, Eldoret, and Mombasa.
A coordinator in Kisumu should usually see only Kisumu participants. A central data manager may need access to all records for monitoring. A statistician may receive de-identified exports across all sites. DAGs allow the database to enforce site-level separation so that users do not accidentally view or edit records outside their responsibility.
DAGs are not the same as user roles. A user role defines what actions a user can perform, such as data entry, export, report viewing, or project design. A DAG defines which records the user can see. Both are needed. A data entry clerk in a site DAG may be allowed to create and edit records, but only for that site. A monitor may be allowed to view records but not edit them.
A central data manager may be outside DAG restrictions or have special access depending on institutional practice.
Implementing DAGs requires a plan for assigning records. Records may be assigned to a DAG manually, through user workflow, or through automated rules depending on project configuration. Thestudyteamshoulddefinehowsiteassignmentoccursandwhoisresponsible
for correcting errors. If a record is assigned to the wrong DAG, users may lose access or the wrong site may see the record.
DAGs also influence reports and exports. Users restricted to a DAG will generally see reports filtered to their own records. Central users may see all records. This is useful for site monitoring, but the data manager should test reports from different user perspectives to confirm that access behaves as intended.