WISQARS™ Fatal Injury Mapping Help Menu

2.5 Map Detail Options

This section includes various options allowing you to control how rates are mapped. Options include the rate interval type, the number of rate intervals (the number of colors to use in the map), and the map color scheme.

Interval Type

Each color in WISQARS Fatal Injury Mapping represents a rate interval (a range of rates). The intervals are automatically determined using rate quantiles (rankings). This is currently the only of type interval provided by WISQARS Fatal Injury Mapping; however, future versions may include other types.

Number of Intervals

You can specify the number of intervals (from 3 up to 9) used to classify the rates in a map. The number of intervals will correspond to the number of colors used in the map.

The number of intervals together with the interval type (see above) will determine how the intervals are formed. For example, if you request 4 intervals (the default) and the interval type is “quantile” (currently the only type available) the intervals will be formed using quartiles.

On occasion, the number of intervals actually displayed in a map will be smaller than the number of intervals requested. This typically occurs in county-level maps that involve many unstable rates or in maps of individual states when the number of intervals requested exceeds the number of counties. When generating maps of individual states having just a few counties, it is suggested that you request a small number of intervals.

Color Scheme

You can select from six different map coloring schemes, including two sequential schemes, two monochrome schemes, and two divergent schemes. These schemes were selected using ColorBrewer, a free Internet tool for choosing good color patterns for maps and graphics. Sequential and monochrome schemes are most useful for highlighting counties or states with high death rates. Divergent schemes are most useful for simultaneously highlighting counties or states that have either high or low death rates.

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