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4530.0 - Crime Victimisation, Australia, 2009–10 Quality Declaration 
Previous ISSUE Released at 11:30 AM (CANBERRA TIME) 17/02/2011   
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EXPLANATORY NOTES


INTRODUCTION

1 The statistics presented in this publication were compiled from data collected on crime victimisation through the Australian Bureau of Statistics' (ABS) 2009-10 Multipurpose Household Survey (MPHS).

2 The MPHS is conducted each financial year throughout Australia from July to June as a supplement to the ABS' monthly Labour Force Survey (LFS) and is designed to provide annual statistics for a number of small, self-contained topics. In 2009-10 the topics were:

  • Crime victimisation
  • Participation in sport and physical recreation
  • Spectator attendance at sporting events
  • Attendance at selected cultural venues and events
  • Patient experience
  • Work related injuries
  • Family characteristics

3 In addition to these topics, information on labour force characteristics, education, income and other demographics was collected.

4 Data for all MPHS topics collected in 2009-10 will be released in separate publications. Expanded Confidentialised Unit Record Files (CURFs) containing detailed data for individual records will also be available following the release of the publications for most topics.

5 This publication presents details from individuals about their own and their household's experience of selected crimes, the reporting of those crimes to police, and perceptions of social disorder in their local area. This publication also presents time series data comparing estimates from the 2009-10 survey with 2008-09 estimates. Crime victimisation data is again being collected for the reference period 2010-11 using the MPHS. That data is expected to be available in early 2012.


SCOPE

6 The scope of the LFS is restricted to people aged 15 years and over and excludes the following:
  • members of the permanent defence forces
  • certain diplomatic personnel of overseas governments, customarily excluded from census and estimated resident populations
  • overseas residents in Australia
  • members of non-Australian defence forces (and their dependants).

7 In addition, the 2009-10 MPHS excluded the following from its scope:
  • people living in very remote parts of Australia
  • people living in non-private dwellings such as hotels, university residences, students at boarding schools, patients in hospitals, residents of homes, (e.g. retirement homes, homes for persons with disabilities, women's shelters), and inmates of prisons.

8 As indicated above, the scope of the 2009-10 MPHS excluded persons living in very remote parts of Australia. The exclusion of people living in these areas is unlikely to impact on state and territory estimates, except in the Northern Territory where they account for approximately 23% of the total population.


COVERAGE

9 The coverage of the 2009-10 MPHS was the same as the scope, except that persons living in Indigenous communities in non-very remote areas were not covered for operational reasons.

10 In the LFS, rules are applied which aim to ensure that each person in coverage is associated with only one dwelling and hence has only one chance of selection in the survey. See Labour Force, Australia (cat. no. 6202.0) for more details.


DATA COLLECTION

11 The MPHS was conducted as a supplement to the monthly LFS. Each month one eighth of the dwellings in the LFS sample were rotated out of the survey. Over 80% of these dwellings were then selected for the MPHS each month. In these dwellings, after the LFS had been fully completed for each person in scope and coverage, a person aged 15 years or over was selected at random (based on a computer algorithm) and asked the various MPHS topic questions in a personal interview. If the randomly selected person was aged 15-17 years, permission was sought from a parent or guardian before conducting the interview. If permission was not given, the parent or guardian was asked the experience of crime questions on behalf of the 15-17 year old, but was not asked the questions about perceptions of social disorder. Only those aged 18 and over were asked questions on sexual assault. Data was collected using Computer Assisted Interviewing (CAI), whereby responses were recorded directly onto an electronic questionnaire in a notebook computer, usually during a telephone interview.

12 For the 2009-10 MPHS, the sample was accumulated over a twelve month period from July 2009 to June 2010.

13 The publication Labour Force, Australia (cat. no. 6202.0) contains information about survey design, sample redesign, scope, coverage and population benchmarks relevant to the monthly LFS, which also applies to the MPHS. It also contains definitions of demographic and labour force characteristics, and information about telephone interviewing relevant to both the monthly LFS and MPHS.


SAMPLE SIZE

14 The sample size may vary for different topics in the MPHS. The initial sample for the 2009-10 MPHS was 38,655 private dwellings, from which one person was randomly selected. Of the 32,760 private dwellings that remained in the survey after sample loss (for example, dwellings selected in the survey which had no residents in scope for the LFS, vacant or derelict dwellings and dwellings under construction), 28,554 or 87% of those dwellings fully responded to the MPHS. The full MPHS dwelling sample (28,554 dwellings/persons) were asked questions on crime victimisation.


WEIGHTING, ESTIMATION AND BENCHMARKING

Weighting

15 Weighting is the process of adjusting results from a sample survey to infer results for the total in-scope population. To do this, a 'weight' is allocated to each sample unit, which, for the MPHS can be either a person or a household. The weight is a value which indicates how many population units are represented by the sample unit. For the MPHS, the first step in calculating weights for each unit was to assign an initial weight, which is the inverse of the probability of being selected in the survey. For example, if the probability of a person being selected in the survey was 1 in 600, then the person would have an initial weight of 600 (i.e. they represent 600 people).


Benchmarking

16 The initial weights were then calibrated to align with independent estimates of the population of interest, referred to as 'benchmarks', in designated categories of sex by age by area of usual residence. Weights calibrated against population benchmarks ensure that the survey estimates conform to the independently estimated distribution of the population rather than the distribution within the sample itself. Calibration to population benchmarks helps to compensate for over or under-enumeration of particular categories of persons/households which may occur due to either the random nature of sampling or non-response.

17 For person estimates, the MPHS was benchmarked to the Estimated Resident Population (ERP) in each state and territory, excluding the ERP living in very remote areas of Australia, at 31 March 2010. For household estimates, the MPHS was benchmarked to independently calculated estimates of the total number of households in Australia. The MPHS estimates do not (and are not intended to) match estimates for the total Australian person/household populations obtained from other sources (which may include persons living in very remote parts of Australia).


Estimation

18 Survey estimates of counts of persons or households are obtained by summing the weights of persons or households with the characteristic of interest. Estimates of non-person counts (e.g. number of attempted break-ins) are obtained by multiplying the characteristic of interest with the weight of the reporting person/household and then aggregating them.


RELIABILITY OF ESTIMATES

19 All sample surveys are subject to error which can be broadly categorised as either:
  • sampling error
  • non-sampling error


Sampling error

20 Sampling error is the difference between the published estimates, derived from a sample of persons, and the value that would have been produced if the total population (as defined for the scope of the survey) had been included in the survey. For more information refer to the Technical Note.


Non-sampling error

21 Non-sampling error may occur in any collection, whether it is based on a sample or a full count such as a census. Sources of non-sampling error include non-response, errors in reporting by respondents or recording of answers by interviewers and errors in coding and processing data. Every effort is made to reduce non-sampling error by careful design and testing of questionnaires, training and supervision of interviewers, and extensive editing and quality control procedures at all stages of data processing.


INTERPRETATION OF RESULTS

22 Crime victim surveys are best suited to measuring crimes against individuals or households with specific victims, who are aware of and recall what happened to them and how it happened, and who are willing to relate what they know to interviewers.

23 This survey covered only selected types of personal and household crimes. Personal crimes covered in the survey were physical assault, threatened assault, robbery and sexual assault. Household crimes covered in the survey were break-ins, attempted break-ins, motor vehicle theft, theft from a motor vehicle, malicious property damage and other theft.

24 Not all types of crime are suitable for measurement by household surveys. No reliable information can be obtained about crimes without specific victims, such as trafficking in narcotics. Crimes of which the victim may not be aware cannot be measured effectively - some crimes involving deception and attempted crimes of many types may fall into this category. It may also be difficult to obtain information about some crimes such as sexual offences and assault committed by other household members due to the sensitivity of the crime and an increased reluctuance to disclose. Some of these crimes may not be fully reflected in the data collected. Household survey data excludes crimes against commercial establishments or government agencies.

25 For this survey the definition of total victims is restricted to those crimes included in the survey and does not represent all crime in Australia.

26 Information collected in this survey is essentially 'as reported' by respondents and hence may differ from that which might be obtained from other sources or via other methodologies. This factor should be considered when interpreting the estimates in this publication and when making comparisons with other data sources.


Statistical measures of crime victimisation

27 The level of victimisation can be expressed in more than one way. The most common measure derived from crime victim surveys is prevalence, that is, the number of the relevant population that have been a victim of a given crime at least once in the reference period. This is known as the 'victimisation rate'. Victimisation rates used in this publication represent the prevalence of selected crimes in Australia, and are generally expressed as a percentage of the total relevant population. Reporting rates used in this publication are expressed as the percentage of victims who reported the most recent incident of crime to police.


DATA COMPARABILITY

28 The 2009-10 Crime Victimisation survey is the second in a new series of regular crime victimisation surveys conducted by the ABS. The first survey in this series (conducted for the 2008-09 reference period) included many of the questions asked in 2009-10. This has allowed some time series comparisons to be made in this publication.

29 The new series was introduced because of a change to the collection methodology. The new method of collection mainly uses personal telephone interviews of selected respondents. Previous data collections since 1990 required respondents to self complete questionnaires and mail these back to the ABS. This difference in mode of collection and changes to survey questions means that data collected using the MPHS is generally not directly comparable with data from previous years' Crime and Safety Surveys.

30 Since 1990, crime and safety surveys have been conducted by the ABS nationally and in specific states and territories at different times. Collections have taken place in the following years:

31 Different crime statistics collections can yield different results. Caution should be taken when comparing data from different surveys and administrative by-product collections that relate to crime and justice issues. For more information on comparisons between sources, please refer to Information Paper: Measuring Crime Victimisation, Australia: The Impact of Different Collection Methodologies, 2002 (cat. no. 4522.0.55.001).

Diagram: Collection reference periods for Crime and Safety Surveys.


Comparability with the 2008-09 Crime Victimisation Survey

32 Most of the questions asked in the 2008-09 Crime Victimisation Survey have been repeated in 2009-10. As a similar methodology has been adopted for both suveys, data on the prevalence of personal and household crimes should be comparable across the two periods.

33 Several questions were added to the Crime Victimisation Survey in 2009-10 which relate to people's perceptions of social disorder in their neighbourhood. These questions replace those on people's feelings of safety and their perceptions of neighbourhood problems asked in 2008-09. While there is some similarity between the social disorder and neighbourhood problem questions, they should not be compared as there are variations in question wording.

34 In the 2008-09 Crime Victimisation Survey, data was not collected in July and August in New South Wales (to avoid overlap with the April 2008 NSW Crime and Safety Survey). In the 2009-10 survey, data was collected for the full 12 months, however this change does not impact on the comparability of the data.


Comparability with police statistics

35 Data for selected crimes recorded by police agencies are available in Recorded Crime - Victims, Australia (cat. no. 4510.0). The Crime Victimisation Survey provides an additional source of data on crime victimisation for the selected crimes, including crime not reported to or detected by police. This survey identifies the nature of this unreported crime, as well as giving information about victims of repeated crimes. The information from the survey should be viewed as a complement to published police statistics on crime.

36 The terms used for the crimes (such as robbery and physical assault) may not necessarily correspond with the legal or police definitions used. This is because responses obtained in this survey are based on the respondent's perception of being the victim of a crime. The definitions of terms used in this survey are based on the wording of the questions asked of the respondent and specifications provided to interviewers. Main definitions can be found in the Glossary.

37 For each crime type, survey respondents were asked how many of the incidents that happened to them in the 12 months prior to the interview became known to the police. As interviews were conducted during 2009-10 the data in this publication relates to crimes occurring over a 12 month period at some time between July 2008 and June 2010. The actual reference period for a particular respondent was determined by the date of their interview. Also, there is no verification a crime report has actually been made for the crime.

38 Another source of variation between the survey results and crimes recorded by police relates to differences in scope. This survey collects information on the personal crimes of robbery and physical assault and threatened assault for all people aged 15 years or over, and sexual assault for people aged 18 years or over. In contrast, police statistics include victims of all ages and any comparisons need to allow for this difference. Furthermore, police record all crimes reported to them in the reference period, whether or not the incidents took place during that period or at an earlier time, and count all distinct instances of victimisation reported.


Comparability with monthly LFS Statistics

39 Due to differences in the scope and sample size of the MPHS and that of the LFS, the estimation procedure may lead to some small variations between labour force estimates from this survey and those obtained from the LFS.


OTHER METHODOLOGICAL ISSUES

40 In the interpretation of the results of the 2009-10 survey, consideration should be given to the representativeness of the sample. This is affected by the response rate and also the fact that the survey covers only people living in private dwellings. It does not include people such as the homeless or those living in special accommodation, who may experience different levels of victimisation than others in the community.


FUTURE SURVEYS

41 The ABS will conduct the MPHS again during the 2010-11 financial year. The 2010-11 MPHS topics are:
  • Crime victimisation
  • Learning and work history
  • Cultural participation
  • Household use of information technology
  • Patient experience
  • Barriers and incentives to labour force participation
  • Retirement and retirement intentions.


ADDITIONAL DATA AVAILABILITY

42 All of the tables included in the publication are also available as Excel spreadsheet datacubes from the ABS website <www.abs.gov.au>. Additional tables at the state and territory level are available for download as Excel spreadsheets only.


DATA AVAILABLE ON REQUEST

43 The ABS has a range of data available from the crime victimisation component of the Multipurpose Household Survey. More detailed breakdowns of some data items are available on request. To request available data, or for more information about our customised data service, contact the National Information and Referral Service on 1300 135 070, or by facsimile on 1300 135 211, or email to <client.services@abs.gov.au>.


CLASSIFICATIONS USED

44 Country of birth data are classified according to the Standard Australian Classification of Countries (Second Edition) (cat. no. 1269.0).

45 Educational attainment is classified according to Australian Standard Classification of Education (ASCED) (cat. no. 1272.0).


GENERAL ACKNOWLEDGEMENT

46 ABS surveys draw extensively on information provided freely by individuals, businesses, governments and other organisations. Their continued cooperation is very much appreciated. Without it the wide range of statistics published by the ABS would not be available. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act 1905.


RELATED PUBLICATIONS

47 Other ABS publications containing information related to Crime victimisation include:

NON-ABS PUBLICATIONS

48 Non-ABS sources that may be of interest can be accessed through the National Centre for Crime and Justice Statistics Topics @ a Glance page on the ABS website.


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