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Introduction to the British Crime Survey Keith Bolling, BMRB Social Research

Introduction to the British Crime Survey Keith Bolling, BMRB Social Research. Outline. Brief history of BCS development Design of the survey since 2001 Fieldwork and response Questionnaire development and content Offence classification Data processing and delivery timetable. E&W. E&W&S.

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Introduction to the British Crime Survey Keith Bolling, BMRB Social Research

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  1. Introduction to the British Crime Survey Keith Bolling, BMRB Social Research

  2. Outline • Brief history of BCS development • Design of the survey since 2001 • Fieldwork and response • Questionnaire development and content • Offence classification • Data processing and delivery timetable

  3. E&W E&W&S E&W E&W&S E&W E&W E&W E&W Coverage History of the British Crime Survey, 1982- 2000 1984 1982 1988 1992 1994 1996 1998 2000

  4. History of the British Crime Survey, 1982- 2000 1984 1982 1988 1992 1994 1996 1998 2000 E&W E&W&S E&W E&W E&W&S E&W E&W E&W Coverage Sample size 10,905 11,030 10,392 10,059 14,617 16,348 14,947 19,457

  5. History of the British Crime Survey, 1982- 2000 1982 1984 1988 1992 1994 1996 1998 2000 E&W&S E&W E&W E&W E&W E&W E&W E&W&S Coverage Sample size 10,905 11,030 10,392 10,059 14,617 16,348 14,947 19,457 80% 78% 77% 77% 77% 83% 79% 74% Response

  6. History of the British Crime Survey, 1982- 2000 1982 1984 1988 1992 1994 1996 1998 2000 E&W&S E&W E&W E&W E&W E&W E&W E&W&S Coverage Sample size 10,905 11,030 10,392 10,059 14,617 16,348 14,947 19,457 80% 78% 77% 77% 77% 83% 79% 74% Response EM 12-15 y.o. None None EM EM EM EM EM Boosts

  7. History of the British Crime Survey, 1982-2000 1982 1984 1988 1992 1994 1996 1998 2000 E&W&S E&W E&W E&W E&W E&W E&W E&W&S Coverage Sample size 10,905 11,030 10,392 10,059 14,617 16,348 14,947 19,457 80% 78% 77% 77% 77% 83% 79% 74% Response EM 12-15 y.o. None None EM EM EM EM EM Boosts Over sampling IC (x3) IC (x1.5) IC (x1.5) IC (x2) IC (x2) IC (x2) IC (x2) PFA

  8. History of the British Crime Survey, 1982-2000 1982 1984 1988 1992 1994 1996 1998 2000 E&W&S E&W E&W E&W E&W E&W E&W E&W&S Coverage Sample size 10,905 11,030 10,392 10,059 14,617 16,348 14,947 19,457 80% 78% 77% 77% 77% 83% 79% 74% Response EM 12-15 y.o. None None EM EM EM EM EM Boosts Over sampling IC (x3) IC (x1.5) IC (x1.5) IC (x2) IC (x2) IC (x2) IC (x2) PFA PAPI CAPI Electoral Roll PAF

  9. Methodological review of the BCS • Significant design changes following a methodological review (Lynn and Elliot, 2000) • Main recommendations were: • Rotation of half the PSUs each year • Over sampling in smaller police force areas • Application of non-response weighting • Better application of low-level geo-identifiers • Continuous fieldwork • Change of reference period

  10. Change to the survey reference period • Prior to 2001 fieldwork was conducted in the first few months of the year (January – April) • Reference period was fixed - the previous calendar year (although respondents asked about last 13-14 months) • Proposed new reference period was rolling– the last 12 months • Experiment carried out in 2001 to test impact of different reference period on victimisation rates

  11. Main characteristics of the survey from 2001 • Core sample size –approximately 37,000 per year • Minimum of 650-700 core interviews in each PFA • Boost samples • Ethnic boost (3,000 per year) • 16-24 year old boost (2000 per year) • Fieldwork managed on monthly basis, with quarterly delivery of data (moving to fiscal year)

  12. Further changes to survey from 2004-5 • Increase of core sample size to approximately 46,000 per year • Minimum of 1,000 core interviews in each PFA • Balancing the precision of national estimates vs. PFA level estimates

  13. Current fieldwork and interviewing • Sample issued equally across the year –approx. 180 assignments per month • Each assignment has 32 addresses selected from across a whole postcode sector • Interviewer has to randomly select one adult (16+) from household for interview • Interview conducted in-home using CAPI • Average interview length of 48 minutes (65 minutes for victims of crime)

  14. BCS response rate over time, 1982 – 2005/6

  15. BCS response rate by GOR, 2005-6 s & Ecst9asy Cannabis & Crack Cannabis & Heroin Heroin & Crack Cannabis & Amph’mne Cannabis, Heroin & Crack Cocaine & Crack Cannabis, Cocaine & Crack Cocaine & Ecstasy Base: All respondents (n=1884)

  16. Ethnic minority boost sample on BCS, 2005-6 • Done by focused enumeration – screening four adjacent addresses to the main sample address • 171,632 addresses screened in 2005-6 • Identified 6,195 eligible households (3.6%) • Achieved 3,098 interviews – a response rate of 50%

  17. Youth (16 – 24 year olds) boost sample on BCS, 2005-6 • Done by screening at core sample addresses after main selection • 40,440 addresses screened in 2005-6 • Identified 3,211 eligible households (7.9%) • Achieved 2,301 interviews – a response rate of 72%

  18. Questionnaire development • Questionnaire development starts about 6 months before start of new survey • Home Office consultation to establish areas of interest and produce first draft • Draft goes through various stages to produce pilot questionnaire • Pilot questionnaire tested using cognitive testing • Sometimes alternative piloting used where appropriate • New questionnaire introduced in April each year

  19. Structure of 2006/7 BCS Questionnaire (part 1) Household Box Main Questionnaire Fear of crime Perception of ASB Screener Questions Victim Form(s) Maximum of 6 Attitudes to CJS Mobile phone theft Module A Contact with police Attitudes to police Module B Attitudes to CJS and sentencing Module C Crime Prevention/ Witnessing crime Module D Worry about crime Social cohesion

  20. Structure of 2006/7 BCS Questionnaire (part 1) Household Box Main Questionnaire Fear of crime Perception of ASB 75% report no crimes 18% report 1 crime 5% report 2 crimes 2% report 3 or more crimes Screener Questions Victim Form(s) Maximum of 6 Attitudes to CJS Mobile phone theft Module A Contact with police Attitudes to police Module B Attitudes to CJS and sentencing Module C Crime Prevention/ Witnessing crime Module D Worry about crime Social cohesion

  21. Structure of 2006/7 BCS Questionnaire (part 2) Module A Contact with police Attitudes to police Module B Attitudes to CJS and sentencing Module C Crime Prevention/ Witnessing crime Module D Worry about crime Social cohesion Night time economy Anti social behaviour Teenagers Drunk and rowdy behaviour Identity theft Anti social behaviour Teenagers Drunk and rowdy behaviour Technology crime Town centre crime Demographics Drug use Inter-personal violence Domestic violence Sexual assault Stalking

  22. Structure of 2006/7 BCS Questionnaire (part 2) Module A Contact with police Attitudes to police Module B Attitudes to CJS and sentencing Module C Crime Prevention/ Witnessing crime Module D Worry about crime Social cohesion Night time economy Anti social behaviour Teenagers Drunk and rowdy behaviour Identity theft Anti social behaviour Teenagers Drunk and rowdy behaviour Technology crime Town centre crime Demographics Drug use Done using CASI 95% acceptance, of which: 88% completed by respondent 12% completed by interviewer Inter-personal violence Domestic violence Sexual assault Stalking

  23. Coding of survey data to offence codes • Major coding exercise to classify all incidents to particular offence types (or out of scope) • Team of office based coders use: • Paper-based summary of each incident • Modular based computerised questionnaire • Not an automated process –needs individual judgement • Uncertain codes and 5% quality check sent to Home Office for verification

  24. BCS Offence Coding Data Management Automatic referral Coder Outcome Supervisor Check (5%) Certain No UNCODED DATA Uncertain Yes Supervisor Coding Automatic referral Home Office Check (5%) Certain No Supervisor Outcome Uncertain Yes Reformat data for Sending to Home Office Data sent to Home Office Data returned by Home Office Disagree Returned coding checked Agree FINAL OFFENCE CODE

  25. Data processing and reporting • Quarterly data processing and delivery cycle • Delivery of data to Home Office 6 weeks after end of fieldwork period • All interviews returned and verified • All coding done • SPSS data files created and checked • Geo-demographic variables attached to data • Design weights derived • Data files delivered as 12 month rolling annual data

  26. Data processing and reporting • Home Office apply calibration weights to data • Calculation of victimisation rates and other key estimates • Publication of results within 12 weeks of end of fieldwork period • Annual data files deposited in archive

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