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5 Students at boarding schools, patients in hospitals, residents of homes (e.g.retirement homes, homes for persons with disabilities), and inmates of prisons were also excluded.
6 The CSS was conducted in both urban and rural areas in all states and territories, but excluded approximately 80,000 persons living in remote and sparsely settled parts of Australia who would otherwise have been within the scope of the survey. The exclusion of these persons will have only a minor impact on any aggregate estimates that are produced for individual states and territories, except the Northern Territory where such persons account for over 20% of the population.
7 The estimates in this publication relate to persons covered by the LFS in April 2002. In the LFS, coverage rules are applied which aim to ensure that 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.
8 CSS questionnaires were either delivered to the selected households by MPS interviewers or mailed to those respondents who completed the MPS by telephone. Respondents were asked to complete the relevant questionnaires and return them by mail. One questionnaire per household contained questions relating to the household as a whole. In addition, all persons in scope were provided with a questionnaire relating to their personal experiences of crime. Males and females aged 18 years and over were supplied with a separate questionnaire about sexual assault. Completion of this sexual assault form was voluntary. The response rate for this form was 73% of females and 72% of males aged 18 years and over who responded to the other personal form in the survey.
RELIABILITY OF THE ESTIMATES
9 Estimates in this publication are subject to sampling and non-sampling errors:
10 Occupation data are classified according to the ASCO - Australian Standard Classification of Occupations, Second Edition, 1997 (cat. no. 1220.0).
11 Industry data are classified according to the Australian and New Zealand Standard Industrial Classification (ANZSIC), 1993 (cat. no. 1292.0).
12 Country of birth data are classified according to the Standard Australian Classification of Countries (SACC), 1998 (cat. no. 1269.0).
13 Offence data are classified according to the Australian Standard Offence Classification, 1997 (cat. no. 1234.0).
14 This publication contains highest level of educational attainment which has been classified according to the Australian Standard Classification of Education (ASCED). The ASCED spans all sectors of the formal Australian education system; that is, School, Vocational Education and Training and Higher Education. The ASCED comprises two classifications: Level of Education and Field of Education. See Australian Standard Classification of Education (ASCED), 2001 (cat. no. 1272.0). For further details on how highest educational attainment is determined, see Education and Work, Australia (cat.no.6227.0).
15 Crime victim surveys are most suitable for 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.
16 This survey covered only selected types of household and personal crimes. Household crimes covered in the survey were break-ins, attempted break-ins, and motor vehicle theft. Personal crimes covered in the survey were robbery, assault and sexual assault.
17 Data on crimes recorded by police are available in Recorded Crime - Victims, Australia (cat.no.4510.0). The CSS provides an additional source of data on crime for selected offences, including crime not reported to or detected by the police. This survey identifies the nature of some crime that is not reported to the police. The survey also gives information on victims of repeated crimes, which is not available from police data. The information from the survey should be viewed as a complement to the published police statistics on crime. Reporting rates refer to the total number of most recent incidents of an offence that were reported to police expressed as a percentage of the total victims of that offence. Police statistics include victims of all ages, whereas this survey collects information for persons aged 15 years and over, and sexual assault is only asked directly for persons aged 18 years and over.
18 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. No reliable data can be collected by household surveys on crimes against commercial establishments or government agencies.
19 For this survey, the definition of total victims is restricted to those offences included in the survey; it by no means represents total crime.
Statistical measures of crime victimisation
20 The level of victimisation can be measured 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 offence at least once in the reference period.
21 Another measure that can be used is incidence. This is the total number of incidents of the offence that occurred in the reference period. As some victims experience repeated incidents of victimisation, incidence numbers are typically higher than prevalence numbers.
22 Rates of prevalence and incidence are both used in this publication, and these are generally expressed as a percentage of the total relevant population.
Interpretation of results
23 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 in interpreting the estimates in this publication.
24 Information was collected on respondents’ perceptions of problems in their neighbourhood. Perceptions are influenced by a number of factors and can change quickly. Care should therefore be taken when analysing or interpreting the data.
COMPARABILITY OF TIME SERIES
25 Revisions are made to population benchmarks for the LFS after each five-yearly Census of Population and Housing. The last such revision was made in February 1999 to take account of the results of the 1996 Census of Population and Housing. Estimates from supplementary surveys conducted from February 1999 and including April 2002 are therefore based on these population benchmarks.
Comparability with previous ABS surveys
26 Since 1990, the ABS has been conducting state-specific Crime and Safety Surveys in New South Wales (annually), 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), often with funding from the state concerned. A national survey was last conducted in 1998, and previous to that in 1993, 1983 and 1975. All of the surveys since 1990 have required respondents to complete the questionnaires themselves and mail these back to the ABS.
27 While an important use of crime victims surveys is to establish the trend of crime and reporting behaviour over time, care must be exercised in the comparison of the results of the 1993 with the 1998 and 2002 surveys for robbery and assault because of significant definitional differences. The household crimes are comparable between the surveys. However, changes in respondents’ attitudes towards crime in the last nine years may have affected their responses to the surveys.
Other methodological issues
28 In the interpretation of the results of the 2002 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 only covers people living in private dwellings. It does not include such people as the homeless or people living in special accommodation, sections of the community which may be heavily victimised. Also, how a respondent completed a questionnaire will depend on their personal circumstances, their interpretation of the questions, and how much they are willing to divulge.
29 Self-enumeration questionnaires may affect the willingness of a person to reveal personal information on issues such as assault and sexual assault. There may also be problems if the respondent’s literacy skills are not adequate to understand a reasonably complex form.
30 The survey also looked at victimisation as discrete incidents, whereas for many victims of violence this is an ongoing situation.
31 Consistency and range edit checks were applied to all forms, mainly during data entry, to ensure that answers were consistent within the household or person record and that they made sense.
32 Victims’ forms were more closely scrutinised. The questions asking respondents to describe the incident were used to check that other questions had been consistently answered. If this resulted in the incident being incorrectly included as a particular offence type, then the incident was either recoded or discounted, as appropriate. This either resulted in an adjustment to the number of incidents, or the respondent being counted as a non-victim of the original offence.
Non-response bias and weighting of data
33 There were a number of cases where the questionnaire was not complete. The most common problem was when questions that should have been answered had been left blank.
34 Missing data were treated in one of the following ways:
35 If an unanswered question affected other questions, then a decision was made on how to code this item. When an unanswered question did not have an effect on other questions, it was coded to ‘not stated’. Generally the proportions of ‘not stated’ were very small. When this was not the case, the number of ‘not stated’ instances have been included overtly in the tables; if the number was small, they have only been included in the total.
36 A complex set of multistage weighting procedures was employed to adjust for non-response and improve the precision of estimates in this survey.
37 The non-response to the sexual assault questionnaire among the respondents of other questionnaires was dealt with first. This was treated as item non-response, and handled by imputation. This was to avoid the need for different weights in the same personal records. The imputation was carried out by choosing a respondent at random within an imputation class, and assigning this selected donor’s value to the non-respondent. Imputation classes were defined using age groups by state and territory.
38 Estimates were then obtained in two stages. In the first stage, adjustment for non-response was carried out based on the demographic composition of the MPS sample, as well as on results of the analysis of the effect of reminder action on the responses obtained.
39 In most surveys there is little information available about non-respondents. In this survey, however, demographic characteristics of most non-respondents were available from the MPS which had a very high response rate. Weighting adjustments were carried out using the distribution of the demographic characteristics from the MPS which were correlated with crime victimisation.
40 For this survey there were two separate reminder follow-ups (by mail for the first reminder, and mail or telephone for the second reminder). Indications of bias due to the difference between respondents and non-respondents were investigated using successive waves of responses. Any significant bias identified was adjusted using data from later waves of responses.
41 The second stage was a complex ratio estimation procedure which ensured that the survey estimates conformed to an independently estimated distribution of population by age, sex, and part of state, rather than to the age, sex and part of state distribution within the sample itself. The procedure also ensured that household estimates conformed to the independently estimated distribution of households by certain household characteristics (number of adults and children in the household) rather than to the distribution among responding households.
Comparison with other ABS surveys
42 There are different crime statistics collections and these can yield differing results. Caution should be taken in comparison across other ABS surveys that address crime and justice issues. An Information Paper: Measuring Crime - The Impact of Different Collection Methodologies, Australia (cat. no. 4521.0) is being prepared for publication shortly.
Comparison with police statistics
43 It should be emphasised that the responses obtained in this survey are based on the respondent’s perception of their having been the victim of an offence. The terms used for the offences (such as robbery, assault) summarise the wording of the questions asked of the respondent, and may not necessarily correspond with the legal or police definitions which are used for each offence.
44 Even though the respondent may indicate that the crime has been reported to the police, there is no verification that a crime report has actually been made for the offence. There are many reasons why an incident which is 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 offence category.
45 Another source of variation between the survey results and crimes recorded by police relates to differences in scope. This survey collects information on robbery and assault only for persons aged 15 years and over, and sexual assault is only asked directly for persons aged 18 years and over, whereas police statistics include victims of all ages and comparisons need to allow for this. Police record all crimes reported to them in the counting period, whether or not the incidents took place during that period or at an earlier time, and count all distinct estimates of victimisation reported.
46 It is also possible that respondents to the survey may have included some incidents which occurred outside the 12 month period. Information was collected on which quarter in the last 12 months the most recent incident occurred, in an attempt to reduce this telescoping effect.
47 For each offence type, survey respondents were asked how many of the incidents that happened to them in the previous 12 months became known to the police. From this the total number of offences that became known to police was estimated. For most offences, the survey estimates of incidents becoming known to the police considerably exceed the number recorded by police. Motor vehicle theft is the only offence category where the differences are not so great.
48 ABS surveys draw extensively on information provided 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.
49 The ABS plans to conduct this survey again in 2005.
50 Other publications which may be of interest include:
51 Current publications and other products released by the ABS are listed in the Catalogue of Publications and Products, Australia (cat. no. 1101.0). The Catalogue is available from any ABS office or the ABS web site. The ABS also issues a daily Release Advice on the web site which details products to be released in the week ahead. The National Centre for Crime and Justice Statistics theme page also contains a wealth of information and useful references and can be accessed through this web site.
52 Non-ABS sources which may be of interest can be accessed through the National Centre for Crime and Justice Statistics theme page on this web site.
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