Crime rate mapping
GIS tools enable the quick calculation of rates for all geographic areas (e.g.
enumeration districts or wards) if the three variables of the rate equation are known.
Once rates have been calculated for each geographic area, these rates can be the
values that are used for creating a thematic map of risk across the partnership area
of interest. This type of rate thematic map can then help identify crime and disorder
hotspots which take into account the underlying population, aiding a more informed
view for targeting crime and disorder reduction resources.
Care in interpreting geographic boundary thematic maps that have been created from
rates still apply (as described in the section geographic boundary thematic
maps). A useful approach to apply when mapping crime or disorder data that
is influenced by an underlying population is to map both a hotspot volume map and
a hotspot rate map. The two maps often tell two separate stories, but complement
each other in the interpretation of crime and disorder patterns.
Map 1 below shows the distribution of residential
burglaries as a hotspot volume map. This map identifies those areas
where there are clusters of residential burglary. However, a map of
this type may just show areas where there are high concentrations of
residential properties – the areas where there is little crime
possibly being rural areas.
Map 2 below shows the distribution of residential
burglary as rates per 1000 households per annum. The rate map takes
into account the distribution of residential housing, identifying
areas of high risk.
Click here for an enlarged example
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