Why does cardinality matter in ad tech?

Response from OpenAI’s ChatGPT:

1. Audience Segmentation & Targeting

  • High-cardinality fields (e.g., cookies, device IDs, hashed emails) are essential for precise targeting.
  • Enables creation of highly specific audience segments, such as “people who visited a specific product page in the last 3 days.”

2. Frequency Capping & Reach Measurement

  • Unique identifiers (high cardinality) help ensure users don’t see the same ad too often.
  • Accurate reach and frequency metrics depend on being able to count distinct users.

3. Attribution Modeling

  • Attribution requires tracking many unique events and users across touchpoints.
  • High cardinality is necessary to follow a user’s journey from impression to conversion.

4. Performance Analytics

  • Granular data (e.g., performance by creative ID or keyword) often has high cardinality.
  • Systems must handle this complexity to enable meaningful insights and decision-making.

5. Data Infrastructure and Cost

  • High cardinality increases storage and compute complexity.
  • Systems like Snowflake or BigQuery must optimize queries to handle large cardinality fields efficiently.
  • Cost control and performance tuning become essential.