How do you troubleshoot Identity Resolution quality issues in Data Cloud?

Identity Resolution quality issues typically manifest as over-merging (too many individuals merged) or under-merging (the same person appears as multiple profiles). Troubleshooting steps:

1. Match Rate Dashboard — review the overall match rate, number of unified individuals, and average records per unified individual. An unusually high average (e.g., 50+ records per person) suggests over-merging.
2. Profile Explorer — look up specific individuals to inspect which source records were merged and via which match rule.
3. Review Match Rules — overly broad probabilistic rules (e.g., matching on first name + city alone) cause over-merging; tighten criteria or add required fields.
4. Data Quality — poor input data quality (missing emails, generic phone numbers like "555-0000") causes under-merging; cleanse source data before ingestion.
5. Reconciliation Rules — if the wrong attribute values are winning, adjust source priority or switch to Last Updated reconciliation.