What is a segment lookalike?
A "lookalike" is a user that is similar to a given segment population. Lookalikes can be useful to prospect users that bear resemblance to a population of users that is of interest to target. For example, it might be a good tactic to target lookalikes in addition to the always-on retargeting of site visitors.
How are lookalikes scored?
Lookalike similarity is computed with a machine learning model that is based on previous observations of the segment population. The scoring model is computed once each day, based on observations from the past week. Processed bid opportunities are scored against the ML model to get a match between 0 and 100%.
The default similarity threshold is currently 70%. During January 2019, it will be possible to manually enter the similarity threshold. A higher threshold means a smaller but more similar lookalike population.
How do I use segment lookalikes?
Lookalike targeting is available as a target type in audiences, and is free to use.
NOTE: Audience size estimations will not be accurate for newly created audiences using lookalikes. Since audience size estimation is currently based on sampling, statistics will accumulate over time.
What about GDPR?
The machine learning model for lookalike targeting is based on hashed and anonymized user data such as time, geo, device and advertiser category, recorded at the time a segment tag fires. As usual since GDPR came into effect, end user consent needs to be retrieved for use of segment tags.
Lookalikes are only available for segments that are set up and populated by your own BidTheatre account - no sharing of lookalike data occurs.