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


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---------------]



• 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



• 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


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 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 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


Schneider et al. (1978)


42%


11%


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


Schneider et al. (1978)

Steinmetz and Docter-

Schamhardt (described by Van

Dijk, 1992)


42% 44%


11% 12%


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%


survey, (RRCD)17%

Total number of cases(= # police cases interviewed) 326

City DC


1970

Reference period 11 months

REVERSE RECORD

CHECK

Dodge (1981)Murphy and Dodge (1981)


83% 67%


survey, (RRCD)17% 33%

Total number of cases(= # police cases interviewed) 326 362

City DC Baltimore


1970 1970

Reference period 11 months 6 months

REVERSE RECORD

CHECK

Dodge (1981)Murphy and Dodge (1981)

Turner (1972)


83% 67% 74%


survey, (RRCD)17% 33% 26%

Total number of cases(= # police cases interviewed) 326 362 394

City DC Baltimore San José


1970 1970 1971

Reference period 11 months 6 months 12 months

REVERSE RECORD

CHECK

Genn (1976)


92%(of which 52% in same month)


survey, (RRCD)8%


237

City London


1972

Reference period 10 months

REVERSE RECORD

CHECK

Genn (1976) Fiselier (1978)


92%(of which 52% in same month)

74-84%(of which

42% in same month)


survey, (RRCD)8% 16 - 26%


237 80

City London Nijmegen


1972 1973

Reference period 10 months 3 years

Not optim

al! (not for these authors (?))

Correcting police figures through VS


• 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


• 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!


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


• 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


• 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?


• 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:


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.

[email protected]

[email protected]


Comments very

welcome!

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Police data are bad, but are victim surveys any better? Applied Research in Crime and Justice...

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