What BISG actually does
BISG combines surname information with geography to estimate probabilities across broad race and ethnicity categories. It is used in research and policy settings when individual-level race or ethnicity is not directly observed.
That means the output is a probability, not a personal identity label and not a certainty about any individual voter.
- Uses surname and geography together
- Produces probabilities, not hard identity labels
- Helps with outreach planning when direct data is missing
- Needs careful interpretation before campaign use
Why campaigns use it
Campaign teams can use BISG-style signals to think more carefully about bilingual planning, community outreach, and segment review. It is often more useful than surname-only matching because geography provides additional context.
The point is not to pretend the model knows a voter. The point is to give the campaign a more transparent planning signal than guesswork.
How VoterFile treats BISG
VoterFile's implemented BISG method treats the result as an outreach-planning probability and keeps the methodology visible because demographic modeling is sensitive. It is not generally active and is never presented as a substitute for self-identification or local campaign knowledge.
Only a separately approved modeled-output lane may expose the signal. Approval requires source, legal, validation, customer, workspace, and output-scope review before a campaign can evaluate whether it is appropriate.
Complete California access review before any file upload.
Submit the campaign, requester, issuing source, viewer list, geography, and intended use. VoterFile does not open upload, import, browse, export, or voter-level modeled output until the California activation checklist is complete.
Questions
Does BISG tell you someone's ethnicity with certainty?
No. BISG produces probabilities from surname and geography signals. It is not a certainty and not self-reported identity.
Why not use surname matching alone?
Surname-only matching ignores local context. BISG can be more useful because it combines surname information with geography.
Does VoterFile use BISG as a support score?
No. Where separately approved and activated, VoterFile treats it as an outreach-planning signal, not as a measure of candidate support.