| Data Quality Problem | Type | Description |
| Single-source Problem | Instance Level | Misspelling Inconsistent values Data entry errors Redundancy Replicas |
| Schema Level | Referential Reliability Poor schema designer Lack of integrity checks Uniqueness checks | |
| Multi-source Problem | Instance Level | Overlapping, challenging and erratic timing, data, and aggregating |
| Schema Level | Naming Clashes Mixed data models and schema design |