When to use

• A data pipeline has just loaded new data and needs validation before downstream reports consume it
• A stakeholder has flagged data quality concerns (wrong totals, unexpected nulls, stale data)
• You need to produce a formal data quality scorecard for a data asset as part of a data governance process
• You are onboarding a new data source and need to understand its quality profile before building on it

Process

1. Null and completeness audit — run scripts/null_counter.py for a column-by-column null profile. Flag columns above acceptable thresholds for the business context.
2. Duplicate detection — run scripts/duplicate_finder.py to identify full-row and key-level duplicates. Determine if duplicates are intentional (versioning) or errors (pipeline fan-out).
3. Referential integrity check — run scripts/referential_integrity.py to validate that foreign key values in child tables exist in parent tables. Report orphan rate per relationship.
4. Value range validation — run scripts/value_range_validator.py with business rules defined in references/business_rule_patterns.md. Flag values outside acceptable ranges.
5. Freshness check — run scripts/freshness_check.py to verify the dataset is up to date — compare the latest record timestamp against the expected lag for this pipeline.
6. Score and classify findings — map each finding to a quality dimension using references/quality_dimensions.md. Assign severity (CRITICAL / HIGH / MEDIUM / LOW).
7. Produce deliverables — fill assets/audit_report_template.html for a shareable report; fill assets/quality_rubric.md for a concise scorecard.

Inputs the skill needs

• Required: dataset (CSV / Parquet / database table reference)
• Required: schema relationships — which columns are primary keys, which are foreign keys to which tables
• Required: business rules — acceptable value ranges, expected value sets, freshness SLA
• Optional: acceptable error rates — at what threshold does a failure become CRITICAL vs. HIGH
• Optional: pipeline schedule — to assess freshness relative to expected update frequency

Output

• assets/audit_report_template.html (filled) — full quality report, shareable with stakeholders
• assets/quality_rubric.md (filled) — one-page quality scorecard with dimension scores
• Script console output — per-check pass/fail counts for each validation script