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 CA Voter treats BISG
CA Voter treats BISG as an outreach-planning probability and keeps the methodology visible because demographic modeling is sensitive. The product does not present BISG as a substitute for self-identification or local campaign knowledge.
Campaigns should review the signal, understand its limits, and decide whether it is appropriate for the segment they are building.
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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 CA Voter use BISG as a support score?
No. CA Voter uses it as an outreach-planning signal, not as a measure of candidate support.