WISQARS™ Fatal Injury Mapping Help Menu
4.1 Mortality (Fatal Injury) Data
Mortality data are obtained from the National Center for Health Statistics (NCHS) National Vital Statistics System (NVSS) annual mortality data files. These annual mortality data files are based on NVSS Mortality Multiple Cause-of-Death data.1 For more information, contact NCHS at (800) 232-4636, contact CDC-INFO, or visit the NCHS/NVSS Web site.
WISQARS Fatal Injury Mapping uses the mortality data to produce maps showing state-level and county-level injury death rates for as many reporting categories as possible according to the intent (manner) of injury, the mechanism (cause) of injury, race/ethnicity, sex, and/or age.
When the total number of deaths used to calculate any rate (crude, age-adjusted, or smoothed) is 20 or less, the rate is considered statistically unstable. States or counties with unstable rates are displayed using a cross-hatch pattern in maps.
In map headings and hover-over windows, and also in data downloads, any unstable rate will at a minimum be annotated as such, and in some instances will be suppressed entirely. Suppression variously depends on the geographic level of the map element (county, state, regional, or national) being referenced and the death count associated with the rate. The suppression rules are as follows:
- A county-level rate that is unstable (associated death count ≤ 20) will always be suppressed.
- A state-level rate that is unstable (associated death count ≤ 20) can be displayed (but annotated as unstable) provided that the death count ≥10 (per data privacy rules); otherwise the rate will be suppressed.
- A regional or national rate that is unstable (associated death count ≤ 20) can be displayed without restriction (but will be annotated as unstable).
For further details on statistical stability/reliability and certain other statistical issues associated with NVSS mortality data, please refer to the National Vital Statistics Report on death data for 2014.1 (To obtain a copy of this report, contact NCHS at (301) 436-8500 or email@example.com or visit the NCHS/NVSS Web site.)