Fundamentals of crime mapping chapter 6

2. Often difficult with crime data

If your analysis or crime map seeks to

understand robbery motivated homicides
within city limits for a given time period, all
known robbery-motivated homicides must be
included in the analysis
If any are excluded, the analysis will be

limited in its power to explain or predict
these crimes.

3. Fixing the problems in your data that can be

done without diminishing the data quality or
inserting error
Repair errors due to “commission”

◦ Error upon entry of data element
Repair errors due to “omission”

◦ This committed by lack of entry for a field or fields
Something most analysts do daily

Being “intimate” with your data helps to

correct these issues

4. Kind of the “Big Picture” of crime mapping

Large scale analysis (citywide), yields large scale

assumptions and cannot be reduced to say a block level
and vice versa
Will control the accuracy needed in the data, both

spatial and attribute accuracy
◦ Eg; If we wanted to do an analysis of tornado damage along the
coast, the coast line graphic would not need to include every
single cove and jut of the coastline, but if our analysis was of one
small bay, then each rock, pier, and beach area might need to be
drawn.
Units of analysis should be useful in the analysis being

performed

5. Official Crime Data

◦ Persons
 Arrestees
 Parolees
 Traffic units
◦ Places
 Schools
 Businesses
◦ Things
 Evidence
 Vehicles
◦ Incidents
 Calls for service
 Reported crimes
 Traffic crashes

6. FBI (http://www.fbi.gov/ucr/ucr.htm)

Weaknesses:

Only reports most serious crime at a location
◦
Definitions may not be the same as state statutes
◦
Voluntary compliance and reporting
◦
UCR counts some crimes by number of victims instead of incidents
◦
Was developed in 1930
◦
Only crime reported to police are captured – self reporting not included
◦
Strengths:

◦ Most states do report
◦ Allows comparison with like-sized agencies across the country
◦ Provides a general picture of crime reported to police

7. FBI (http://www.fbi.gov/ucr/ucr.htm)

Weaknesses:

◦ Reports all crimes occurring at location
◦ Only a few states report NIBRS data
Strengths:

◦ Reports all crimes occurring at location
◦ More robust definitions

8. Citizen generated requests for police services

Officer initiated activity

◦ Location citizen gave for call, may not be where
incident actually happened
◦ Location may be an intersection and not a specific
address
◦ Depending on how it is captured it may not
geocode and can thus, not be mapped
◦ What the call came in as, may not be what the
officer determines was the real problem
◦ Not necessarily a picture of “crime” but of citizen
desire for police presence only

9. Official Crime Data

◦ Persons
 Arrestees, or persons listed in police reports
(victim, witnesses, suspects)
 Parolees/probationers
 Traffic units/passengers
◦ Places
 Schools, hotels, police stations, massage parlors
 Businesses, etc
◦ Things
 Evidence
 Vehicles, guns, etc
◦ Incidents
 Calls for service
 Reported crimes
 Traffic crashes

10. Can capture crime data not reported to police

(much is not)
◦ There is no way to verify if a respondent is
providing truthful and accurate information
◦ Information on homicides is not collected. (“Dead
men can tell no tales”)
◦ Crime victims under the age of 12 years are
unaccounted for Victimless crime is unaccounted
for

12. Data not collected by police departments, but

that can be used for crime mapping
US Census
◦
City sales tax and licensing
◦
Google, Yahoo, US West Dex Yellow Pages
◦
Political boundaries from local, county and state
◦
Local social agencies like Department of Economic
◦
Security
◦ GIS data at local universities
◦ Other city departments
◦ Etc.

13. Microsoft

Access – database
◦
Excel – spreadsheet
◦
Word – word processor
◦
Powerpoint – presentation of information
◦
Statistical Packages

◦ Excel add-in Analysis toolpak
◦ SPSS
◦ SAS
CrimeStat III

◦ Spatial statistics

14. Off the shelf additional programs

Crime View
◦
Crime Analysis Tools
◦
Hawthe’s Tools
◦
Curve expert (regression curve analysis software)
◦
Coplink
◦
Oracle spatial
◦
SQL Server
◦
ATAC
◦
Etc
◦

15. Criminals do not care about imaginary borders

along the roads dividing adjacent cities – why
should we?
Data sharing has increased since 911, but still

have a way to go
Biggest problem is politics not technology right

now
Data sharing systems are inter-agency and can

be expensive
We need more privacy impact assessments on all

the data that is being shared
Movement toward NIEM

◦ http://www.niem.gov/

16. Knowing which data sources to use and how

to share the completed analysis (whether in
report or map form) is diverse and complex.
Understanding and clearly articulating the

limitations of the data used is also
necessary
Understanding the legal and ethical issues

involved with distributing crime
maps, data, and analysis is imperative for
crime analysts