In BigQuery, traffic attribution data is available at the user (first visit), session, and event levels, corresponding to the different scopes used in Google Analytics:
- User-scoped:Provides attribution for the user's first arrival.
To determine first user traffic source, you can use the
traffic_sourcedimensions associated with thefirst_visitevent in the BigQuery export:-
traffic_source.source -
traffic_source.medium -
traffic_source.name
-
- Session-scoped:Provides attribution for the source of each individual
session. To determine session traffic source, use the
session_traffic_source_last_clickrecord. This record is available for every event and reflects the session-scoped last-click attribution data. Common fields include:-
session_traffic_source_last_click.manual_campaign.source -
session_traffic_source_last_click.manual_campaign.medium -
session_traffic_source_last_click.manual_campaign.campaign_name -
session_traffic_source_last_click.google_ads_campaign.campaign_name
-
- Event-scoped:Provides attribution for conversion events, using the
cross-channel last-click attribution model. Every event in the BigQuery
export has
traffic_sourcepopulated. For conversion events, these fields contain the attribution data for that event:-
traffic_source.source -
traffic_source.medium -
traffic_source.name
-
Use these fields to perform detailed attribution analysis within BigQuery and join this data with other first-party datasets for enhanced insights.

