Jieying Ding, Ujjwal Kumar, Henk Eskes , Henk Klein- Baltink
Police data are bad, but are victim surveys any better? Applied Research in Crime and Justice...
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Transcript of Police data are bad, but are victim surveys any better? Applied Research in Crime and Justice...
Police data are bad, but
are victim surveys any better?
Applied Research in Crime and Justice Conference Sydney, 2013
Henk ElffersNetherlands Institute for the Study of Crime and Law Enforcement NSCR, Amsterdam
VU University AmsterdamGriffith University Brisbane
Based on work together with Margit Averdijk Eidgenössische Technische Hochschule ETH, Zürich
Police bad, victim surveys better? / 2
Measuring the amount of crimePolice registration
Dependent on • reporting to police (“get cases”)
– burglary, assault, …– influenced by seriousness, relation offender-victim,
own involvement, definition, …
• priority of police attention (“fetch cases”)– drunken driving, drugs, …– short term planning policy– low police efficacy
Police bad, victim surveys better? / 3
Measuring the amount of crimeVictim survey
• Sample (response bias)• “have you in the past 12 months been a
victim of – crime1, crime2, … , crime10– Have you reported that to the police?”
• A selection of crimes only• Memory problems
– Forgetting– Telescoping: -----X----(-----X---------------]
Police bad, victim surveys better? / 4
Measuring the amount of crimeVictim survey
• Willingness to participate– Sensitive topics, Burden
• Standard survey problems• Misinterpretation
– “Violence” = “Foul language”?
• Social desirability– First questions on how awful crime is– Then admitting not even to have reported?
• Substitution (victimhood of partner, children)• Manipulation
Police bad, victim surveys better? / 5
Measuring the amount of crimeVictim survey
• If 1 / n says to have reported, can we than say that the amount of crime is n * as large as police registered data would suggest?
• Only if all problems mentioned are minor
• The inventors of the victim survey did research in the ‘70’s to check that
Police bad, victim surveys better? / 6
Forward and reverse record checks
• If we have a sample of VS-responders, that say they have reported a victimization, can we find that incident back in the police data?– Forward record check
• If we have a case reported to the police, and the victim is surveyed, does he mention that case?– Reverse record check
Police bad, victim surveys better? / 7
Police register
VS: no victimization reported to
police
A C
B D
•Forward record check discrepancy:
•how many cases of victimization that were reported, according to victim, were not found in the police register
•Reverse record check discrepancy:
• how many cases of victimization known to the police are not reported in a survey
VS: victimization reported to
police
Victimisation survey
C/(C+D)
B/(B+D)
Police bad, victim surveys better? / 8
Police register
VS: no victimization reported to
police
A C
B D
•Total discrepancy:
•how many cases from the survey are not found identically in both registers
(B + C) / (A + B + C + D)
VS: victimization reported to
police
Victimisation survey
FORWARD RECORD CHECK
Match: Percentage of crimes that victims claim they reported to the police and that was found in police data within reference period
Forward telescoping: Percentage of crimes that victims claims they reported to the police and that was found in police data but before reference period
No match: Percentage of crimes that victims claim they reported crime to police but that was not found in
police data (FRCD)Total number of cases (= # crimes claimed to be reported to the police)
CityYear in which study was conductedReference period
FORWARD RECORD CHECK
Schneider et al. (1978)
Match: Percentage of crimes that victims claim they reported to the police and that was found in police data within reference period
42%
Forward telescoping: Percentage of crimes that victims claims they reported to the police and that was found in police data but before reference period
11%
No match: Percentage of crimes that victims claim they reported crime to police but that was not found in
police data (FRCD)47%
Total number of cases (= # crimes claimed to be reported to the police)
399
City PortlandYear in which study was conducted 1974Reference period 12 months
FORWARD RECORD CHECK
Schneider et al. (1978)
Steinmetz and Docter-
Schamhardt (described by Van
Dijk, 1992)
Match: Percentage of crimes that victims claim they reported to the police and that was found in police data within reference period
42% 44%
Forward telescoping: Percentage of crimes that victims claims they reported to the police and that was found in police data but before reference period
11% 12%
No match: Percentage of crimes that victims claim they reported crime to police but that was not found in
police data (FRCD)47% 44%
Total number of cases (= # crimes claimed to be reported to the police)
399 108
City Portland Utrecht Year in which study was conducted 1974 1978Reference period 12 months 12 months
it has not hampered the development
of a VS-tradition
REVERSE RECORD
CHECKMatch: Percentage of police registered crimes that are also reported in victimization survey
No match: Percentage of police registered crimes not reported in victimization
survey, (RRCD)
Total number of cases(= # police cases interviewed)
City
Year in which study was conducted
Reference period
REVERSE RECORD
CHECK
Dodge (1981)
Match: Percentage of police registered crimes that are also reported in victimization survey
83%
No match: Percentage of police registered crimes not reported in victimization
survey, (RRCD)17%
Total number of cases(= # police cases interviewed) 326
City DC
Year in which study was conducted
1970
Reference period 11 months
REVERSE RECORD
CHECK
Dodge (1981)Murphy and Dodge (1981)
Match: Percentage of police registered crimes that are also reported in victimization survey
83% 67%
No match: Percentage of police registered crimes not reported in victimization
survey, (RRCD)17% 33%
Total number of cases(= # police cases interviewed) 326 362
City DC Baltimore
Year in which study was conducted
1970 1970
Reference period 11 months 6 months
REVERSE RECORD
CHECK
Dodge (1981)Murphy and Dodge (1981)
Turner (1972)
Match: Percentage of police registered crimes that are also reported in victimization survey
83% 67% 74%
No match: Percentage of police registered crimes not reported in victimization
survey, (RRCD)17% 33% 26%
Total number of cases(= # police cases interviewed) 326 362 394
City DC Baltimore San José
Year in which study was conducted
1970 1970 1971
Reference period 11 months 6 months 12 months
REVERSE RECORD
CHECK
Genn (1976)
Match: Percentage of police registered crimes that are also reported in victimization survey
92%(of which 52% in same month)
No match: Percentage of police registered crimes not reported in victimization
survey, (RRCD)8%
Total number of cases(= # police cases interviewed)
237
City London
Year in which study was conducted
1972
Reference period 10 months
REVERSE RECORD
CHECK
Genn (1976) Fiselier (1978)
Match: Percentage of police registered crimes that are also reported in victimization survey
92%(of which 52% in same month)
74-84%(of which
42% in same month)
No match: Percentage of police registered crimes not reported in victimization
survey, (RRCD)8% 16 - 26%
Total number of cases(= # police cases interviewed)
237 80
City London Nijmegen
Year in which study was conducted
1972 1973
Reference period 10 months 3 years
Not optim
al! (not for these authors (?))
Correcting police figures through VS
Police bad, victim surveys better? / 18
• On quicksand
BUT:
• Rather small studies
• Long ago– Survey methodology improved (CATI)– Police registratiuon improved (computerized)
• Time to update these studies
Amsterdam Mutual Coverage Study
Police bad, victim surveys better? / 19
• Large scale
• Total Amsterdam-Amstelland police database of reported incidents– January 2007-2006-2005-2004
• N = 281181
• City of Amsterdam continuous victim survey (O+S)– 10 months, April 2006 – January 2007
• N = 8887, 4300 victims, 1675 declare to have reported
Thanks!
Thanks!
Police bad, victim surveys better? / 20
Special conditions
• Exemption from the Privacy Chamber• All analysis on the police premises• Coupling on name/address/gender/age
– After coupling immediate removal of all ID
• Data or not available for other researchers without getting access privileges again
Coupling
Police bad, victim surveys better? / 21
• Coupling very tedious– Police uses official census names– VS telephone register (household), noting down
names and addresses as understood• Maiden names• Multiple spellings• Family members• …
– Smart algorithm on name, address, age, gender– Not perfect, but not bad either
Amsterdam Mutual Coverage Study
Results
Victimization reported according to
victimization survey?
No Yes Total
Victimization registered by
police?
No A = 6,665 C = 1,091 7,756
Yes B = 547 D = 584 1,131
Total 7,212 1,675 8,887RRCD = 48% FRCD = 65% TDC = 18%
Amsterdam Mutual Coverage Study Results
# Respondents who said in interview
they reported crime to police
1. Direct match: Also found in police registration, in reference period2. Forward telescoping: Also found in police registration, but before reference period3. Household member match: Also found in police registration, but refers to other household member (personal crimes only)4. No match: Not found in police registration Total
Amsterdam Mutual Coverage Study Results
# Respondents who said in interview
they reported crime to police
1. Direct match: Also found in police registration, in reference period
584 (35%)
2. Forward telescoping: Also found in police registration, but before reference period
475 (28%)
3. Household member match: Also found in police registration, but refers to other household member (personal crimes only)
123 (7%)
4. No match: Not found in police registration
493 (29%)
Total 1,675 (100%)
Conclusion
Police bad, victim surveys better? / 25
• Victim surveys and police registration are shockingly different
• VS: telescoping is major problem– (overestimating crime by more than ¼ – Newer methods mitigate this problem (?)
• VS: victimisation of householdmembers mentioned 7%
• VS: 29% could not be found at all• Only 1/3 found back unreservedly
Too bad !
VS or PR?
Police bad, victim surveys better? / 26
• My impression: more a VS than a PR problem
• VS: more concern needed for quality– Period, bounding questions– Question interpretation?
• Cognitive labwork necessary
• PR: Observation studies during police registration
Published as:
Police bad, victim surveys better? / 27
Averdijk, M. & H. Elffers (2012)
The Discrepancy between Survey-Based Victim Accounts and Police Reports Data Revisited.
International Review of Victimology 18/2, 91-107
DOI: 10.1177/0269758011432955.
Police bad, victim surveys better? / 28
Comments very
welcome!