The one fire metric that is genuinely comparable across every New Jersey county is the civilian fire-death rate: average annual civilian fire deaths per 100,000 residents over 2020-2021. Deaths come from the New Jersey Department of Health's NJSHAD injury-mortality data (New Jersey Vital Statistics — fire/flame/smoke deaths per the NCHS external-cause-of-injury matrix, ICD-10 X00–X09, all injury intents, residence-based, un-suppressed exact counts); population comes from the U.S. Census Bureau. The rate is a direct, reproducible calculation —(5-year deaths ÷ 5) ÷ population × 100,000— not an estimate.

The Overall Fireground Index score normalizes that rate across the 21 counties: a z-score, inverted so a lower fire-death rate yields a higher score, centered at 50and clamped to 0-100:score = clamp(50 − z × 18, 0, 100). There is no black box. The platform's multi-dimensional scoring engine is reserved for when multiple comparable metrics exist; with one comparable fire metric today, this single transparent normalization is used instead.

Where a county publishes an incident/response figure, it is shown as sourced context with its exact definition and reporting year. These counts use incompatible definitions across counties (total incidents vs. calls for service vs. unit responses, and fiscal- vs. calendar-year), so they are never normalized into a cross-county comparison — that would be misleading.

Civilian injuries, firefighter injuries, and fire dollar loss have no authoritative per-county public source, so they are shown as “Data not publicly available”with the sources investigated. Missing data reduces Data Confidence; it never blanks a county.

New Jersey’s fire deaths here are death-certificate (vital-statistics)counts from the New Jersey Department of Health, not fire-incident (NJFIRS) counts. Every New Jersey county uses the same NJ DOH source, so the index is internally consistent; because different states may use different death-count bases, scores are ranked within New Jersey and are not a cross-state comparison.

Data Confidence communicates how much verifiable public evidence backs a county: the authority of its sources, how many public metrics exist, and how statistically reliable the outcome data is (a county with 0-2 fire deaths over five years has a real but uncertain rate). A data-rich county reads differently from a data-sparse one — and that difference is itself information. Confidence is never based on whether every county reports identically.