How to evaluate crime risk data
The ten-check buyer audit
| # | Check | Evidence to request |
|---|---|---|
| 1 | Source provenance | Primary source URL, file or endpoint, access date, and source year |
| 2 | Agency coverage | Participating ORIs, mapping rules, and explicit missing-data flags |
| 3 | Geographic fit | Boundary or service-area definition for every place |
| 4 | Offense definition | Codes, labels, inclusions, exclusions, and system used |
| 5 | Zero handling | Rule separating a reported zero from null or unavailable |
| 6 | Normalization | Population source, year, geography, and per-capita formula |
| 7 | Recency | Latest complete period plus update schedule |
| 8 | Score construction | Weights, caps, shrinkage, and eligibility rules |
| 9 | Licensing | Permitted use, redistribution, attribution, and retention terms |
| 10 | Reproducibility | Version identifier, QA sample, and correction process |
Red flags
- “Nationwide coverage” with no agency participation table.
- A zero that cannot be traced to a reported source value.
- City scores built from county data without a visible substitution notice.
- Rankings that mix reporting years or population geographies without qualification.
- Proprietary scores with no version, methodology, or correction route.
Match evidence to the decision
Newsrooms may prioritize transparent sources and reproducible charts. Insurance and investment teams may need consistent licensing, batch delivery, and audit logs. Policy researchers may require longitudinal fields and sensitivity tests. In every case, coverage should be a first-class field rather than a footnote.
Test a sample before accepting a dataset
- Ask for one populated record, one reported zero and one unavailable record. Require a source reference and explanation for each.
- Recalculate one per-capita rate from the supplied count and matched population: count divided by population, multiplied by 100,000. Treat rounding separately from a denominator mismatch.
- Compare two years for the same agency and offense. Check reporting months, definitions and participation before calling the difference a trend.
- Trace one city mapping to its agency service area. Ask for a visible limitation if the geographic units do not match.
- Retain the vendor version, retrieved date and correction contact with your review.
Worked arithmetic example
In a hypothetical record, 20 reported offenses and a matching covered population of 10,000 give a rate of 200 per 100,000. This is an arithmetic example, not a claim about any real city. An unavailable count cannot be turned into zero, and an annual population cannot automatically explain every monthly rate.
Record an acceptance decision
Accept a record only when the source, period, geography, definition and denominator can be reconciled. Mark incomplete evidence for review and keep it out of rankings until resolved. This distinguishes a missing-data problem from a place with a low reported count.
Use the reporting-system guide for terminology and the product comparison guide to choose a delivery format that fits your question.