Limitations of hot spot maps
Concentrations of victimization sometimes
can be shown with maps, but often they
cannot. If victimization risk is in part geographical,
then maps are useful. A citywide
dot map of gas stations with two or
more robberies within the last 6 months
shows concentration at two levels. The
dots depict concentrations of robbery at
specific places. Groupings of dots depict
streets or neighborhoods with concentrations
of repeat robbery gas stations. Dot
maps for this type of victimization makes
some sense, but they do not work for all
forms of victimization concentration. If victims
are mobile, street or area maps might
be more useful. However, the use of maps
is limited for some forms of victimization
analysis. If the population of potential victims
is spread throughout an area (not
concentrating at places, along streets, or
within neighborhoods), the analyst would
be better off using an analytical technique
other than maps to convey the concentration.
For example, taxicab robberies may
be spread quite thinly across a city. The
relevant features of the robbery victims
might be related to the cab companies,
the drivers’ ages, hours of operation,
installed security within cabs, or a host of
factors that cannot be shown on a map.
Police officers trying to investigate or prevent
such robberies would find maps less
useful than bar charts showing the characteristics
of victims and nonvictims.