Australian Bureau of Statistics
4530.0 - Crime Victimisation, Australia, 2008-09 Quality Declaration
Previous ISSUE Released at 11:30 AM (CANBERRA TIME) 18/02/2010 First Issue
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3 For all topics, information on labour force characteristics, education, income and other demographics are also available.
4 The crime victimisation topic collected information from individuals about their own and their household's experience of selected crimes, the reporting of those crimes to police, and perceptions of safety and problems in the neighbourhood.
5 Data for other MPHS topics collected in 2008-09 have been released in separate ABS publications.
6 The MPHS will be the vehicle for collection of crime victimisation data for the 2009-10 reference period and annually thereafter.
7 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 supplementary surveys. It also contains definitions of demographic and labour force characteristics, and information about telephone interviewing relevant to both the monthly LFS and supplementary surveys.
8 ABS interviewers conducted personal interviews by either telephone or at selected dwellings during 2008-09. Each month a sample of dwellings was selected for the MPHS from the responding households in the LFS. After the LFS had been fully completed for each person at these dwellings, a usual resident aged 15 years or over was selected at random and asked the additional MPHS questions in a personal interview predominantly by telephone. Where the randomly selected person was aged between 15 and 17 years a parent or guardian was allowed to opt to respond on their behalf. Information about perceived neighbourhood problems excludes data for those aged between 15 years and 17 years where a proxy responded on their behalf. Information was collected using Computer Assisted Interviewing, whereby responses were recorded directly onto an electronic questionnaire in a notebook computer.
9 The sample was accumulated over a 12-month period (July 2008 to June 2009). The Crime Victimisation topic was not collected in New South Wales in July and August to avoid having respondents being asked similar questions to those they were asked in the April 2008 NSW Crime and Safety Survey. The estimation methodology used ensures that estimates for this topic are not impacted by the abbreviated collection period in New South Wales.
SCOPE AND COVERAGE
10 The scope of the LFS is restricted to people aged 15 years and over and excludes the following:
11 In addition, the 2008-09 MPHS excluded the following:
12 The 2008-09 MPHS was conducted in both urban and rural areas in all states and territories, but excluded people living in very remote parts of Australia. The exclusion of these people is expected to have only a minor impact on any aggregate estimates that are produced for individual states and territories, except in the Northern Territory where such people account for around 23% of the population.
13 The LFS applies coverage rules that aim to ensure each person 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.
14 The initial total sample for the crime victimisation topic included in the MPHS 2008-09 consisted of 34,513 private dwelling households, which is approximately double the standard MPHS sample. Of the 29,261 private dwelling households that remained in the survey after sample loss (i.e. households with LFS non-response, no residents in scope for the LFS, vacant or derelict dwellings and dwellings under construction), approximately 25,601 or 87% were fully responding to the crime victimisation topic.
15 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 from the LFS. For further information on the sample size of the LFS, refer to the ABS information paper Information Paper: Labour Force Survey Sample Design, Nov 2007 (Third edition) (cat. no. 6269.0).
WEIGHTING, ESTIMATION AND BENCHMARKING
16 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 that indicates how many population units the sample unit represents. The first step in calculating weights for each unit is to assign an initial weight, which is the inverse of the probability of being selected in the survey. The initial weights are then calibrated to align with independent estimates of the population of interest, referred to as 'benchmarks'. Weights are calibrated against population benchmarks to ensure survey estimates conform to the independently estimated distribution of the population rather than the distribution within the sample itself.
17 The estimation procedure for these surveys ensures that estimates of persons calibrate exactly to independently produced population totals at broad levels. The known population totals are produced according to the scope of the survey. The same is true for estimates of households produced in this survey. However, in these cases the household benchmarks are actually estimates themselves and not strictly known population totals.
18 Survey estimates are benchmarked to persons or households within the scope of the survey. The sample for the MPHS was benchmarked against demographic estimates corresponding to December 2008, midway through the MPHS enumeration cycle. For example, the MPHS was benchmarked to the estimated civilian population aged 15 years or over living in private dwellings in each state and territory excluding persons out of scope. Survey estimates of counts of persons or households are obtained by summing the weights of persons or households with the characteristics of interest.
RELIABILITY OF ESTIMATES
19 Estimates provided in this publication are subject to sampling and non-sampling error.
20 Sampling error is the difference between the published estimates, derived from a sample of people or households, and the value that would have been produced if all people or households in scope of the survey had been included. For more information refer to the Technical Note.
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. In addition, the way respondents respond to the survey's questions will depend on their personal circumstances, their interpretation of the questions, and how much they are willing to divulge.
22 Offence data are classified according to the Australian Standard Offence Classification, 2008 (Second Edition) (cat. no. 1234.0).
23 Country of birth data are classified according to the Standard Australian Classification of Countries (Second Edition) (cat. no. 1269.0).
CONFIDENTIALISED UNIT RECORD FILE
24 Confidentialised unit record files (CURF) contain confidentialised microdata from surveys, thereby facilitating interrogation and analysis of data.
25 For the crime victimisation topic in the 2008-09 MPHS survey, one expanded CURF will be released in 2010. For more information on expanded CURFs refer to the ABS Technical Manual for MPHS expanded CURFs (cat. no. 4100.0).
26 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.
27 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.
28 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 instances of fraud 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. Some of these crimes may not be fully reflected in the data collected. Household survey data excludes crimes against commercial establishments or government agencies.
29 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.
Statistical measures of crime victimisation
30 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. Victimisation rates used in this publication represent the prevalence of selected crimes in Australia, and are generally expressed as a proportion of the total relevant population.
31 Information recorded 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.
32 Information was also collected on respondents' perceptions of problems in the neighbourhood. Perceptions are influenced by a number of factors and can change quickly. Care should therefore be taken when analysing or interpreting these data.
Comparability with previous ABS Crime and Safety Surveys
33 A National Crime and Safety Survey was last conducted in 2005, and previous to that in 2002, 1998, 1993, 1983 and 1975. Since 1990 the ABS has conducted state-specific Crime and Safety Surveys in New South Wales (1994, 1995, 1996, 1997, 1999, 2000, 2001, 2003, 2004, 2006, 2007, 2008), Western Australia (1991, 1995, 1999 and 2000), South Australia (1991, 1995 and 2000), Victoria (1994 and 1995), Tasmania (1998) and Queensland and the Australian Capital Territory (1995). All of the surveys since 1990 have required respondents to self-complete the questionnaires and mail these back to the ABS.
34 The 2008-09 Crime Victimisation Survey has been redesigned using a new method of collection. The 2008-09 MPHS data were collected by personal interviews by telephone or at selected dwellings. Due to differences in mode of data collection and survey questions, crime victimisation data from the 2008-09 Crime Victimisation Survey onwards is not directly comparable with data from previous years' Crime and Safety Surveys.
Comparability with 2005 National Crime and Safety Survey
35 Crime victimisation data for 2005 were obtained from the National Crime and Safety Survey. Shortly after the April 2005 LFS interview, paper Crime and Safety questionnaires were mailed to LFS respondents. Each respondent in the household was asked to complete a questionnaire relating to his or her personal experience of crime, and return it to the ABS by mail. One questionnaire per household also contained questions relating to experiences of household crime, to be answered by one respondent on behalf of the household as a whole.
36 The ABS has investigated the statistical significance of data changes between the 2005 National Crime and Safety Survey and the 2008-09 Crime Victimisation Survey using the MPHS. The analysis found significant differences in the rates of three of six selected crime types (attempted break-in, robbery and assault), as the table below shows. However, it is difficult to identify the underlying reason for this change due to the number of differences between the two surveys, as well as the three years separating their collection and a possible actual change in the incidence of crime. Differences between the two surveys are described below. Where results are not statistically significant it can not be assumed that there is no impact.
37 In 2008-09 respondents were asked screening questions in the feelings of safety topic. The questions were: 'In the last 12 months, have you spent time at home by yourself (during the day/after dark)'. Respondents who answered 'yes' to one or both of these question were asked to rate on a scale how safe they felt at home by themselves during the day/after dark. In 2005 all respondents were asked to rate how safe or unsafe they felt at home by themselves during the day/after dark.
38 In 2008-09 separate questions were asked about incidents of assault and incidents of threatened assault, whereas in 2005 data collected for incidents of assault and threatened assault were output at an aggregate level.
39 In 2005 respondents were asked whether anyone had stolen or tried to steal anything from them in the last 12 months, whereas in 2008-09 respondents were asked whether anyone had stolen anything belonging to them or to a member of their household.
40 In 2008-09 data about theft from a motor vehicle, other thefts and malicious property damage were collected for the first time.
41 Some data collected in the 2005 National Crime and Safety Survey were not collected in 2008-09 Crime Victimisation Survey. A list of data items for the 2008-09 Crime Victimisation Survey is available in an Excel spreadsheet datacube from the ABS website. For a list of data items collected in the 2005 National Crime and Safety Survey, refer to ABS publication Crime and Safety, Australia, 2005 (cat. no. 4509.0).
Comparison with other ABS surveys
42 The ABS produces different crime statistics collections and these can yield different results. Caution should be taken in comparison across other ABS surveys and administrative by-product data that address 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)
Comparison with police statistics
43 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. There are two types of reporting rates in this publication. The reporting rates in Tables 1 and 2 refer to the proportion of victims who reported the most recent incident of a crime to police. The reporting rates in Table 5 refer to the total number of incidents of a crime reported to police expressed as a percentage of the total number of incidents of that crime experienced. Police statistics include victims of all ages, whereas this survey collects information for people aged 15 years or over, and sexual assault is only asked directly for people aged 18 years or over.
44 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, and can be found in the Glossary of this publication.
45 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 2008-09 the data in this publication relates to crimes occurring over a 12 month period at some time between July 2007 and June 2009. 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. There are many reasons why an incident reported to police may not be recorded as a crime. Victims may advise police of a matter but not seek to have it dealt with as a crime. This is especially true of incidents where the offender is related, or otherwise known, to the victim. The information received by police may not be sufficient to allow them to determine whether a crime has been committed, or what kind of offence has been committed. The incident may also have been coded to a different crime category.
46 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.
OTHER METHODOLOGICAL ISSUES
47 In the interpretation of the results of the 2008-09 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, sections of the community that may be heavily victimised.
48 In order to derive the total number of incidents for the selected crimes the survey looked at victimisation as discrete incidents, whereas for many victims of violence this can be an ongoing situation.
49 ABS publications 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.
50 Current publications and other products released by the ABS are listed in the Catalogue of Publications and Products (cat. no. 1101.0). The catalogue is available from the ABS website. The ABS also issues a daily Release Advice on the website that details products to be released in the week ahead. In addition, the National Centre for Crime and Justice Statistics theme page contains a wealth of information and useful references and this site can be accessed through the ABS website.
51 Non-ABS sources that may be of interest can be accessed through the National Centre for Crime and Justice Statistics theme page on the ABS website.
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This page last updated 16 February 2011