11 Comparing the SCJS with Other Data Sources
11.1 Comparison with police recorded crime
The SCJS provides estimates of the level of crime in Scotland. It includes crimes that are not reported to or recorded by the police, but is limited to crimes against adults resident in households, and also does not cover all crime types (section 7.1.2).
Police recorded crime is a measure of those crimes reported to the police and recorded by them as a crime or offence.
In order to compare the estimates of crime from the SCJS and police recorded crime statistics, a comparable subset of crime was created for a set of crimes that are covered by both measures. 67% of 'all SCJS crime' as measured by the SCJS 2009/10 falls into categories that can be compared with crimes recorded by the police. The SCJS 2009/10 estimated 40% of comparable crime to be reported to the police.
It is possible to make comparisons between the SCJS and police recorded crime statistics for three crime groups (Figure 4):
- Vandalism (including motor vehicle vandalism and property vandalism);
- Acquisitive crime (including bicycle theft, housebreaking and theft of motor vehicles);
- Violent crime (including assault and robbery).
Section 7.3.1 provides further information about these crime groups.
To enable comparison, estimates of the total number of comparable crimes in Scotland were obtained by grossing up the number of crimes identified in the SCJS using the General Register Office for Scotland ( GROS) estimates (section 7.2).
'All SCJS crime' estimates are based on interviews conducted between the 1 st of April 2009 and the 31 st of March 2010. Interviews were conducted continuously through this fieldwork period. Respondents were asked about crimes they experienced in the 12 months prior to the interview (the reference period - section 5.1). The rolling reference period used in the SCJS means that the data collected centres around March 2009, the only month to be included in all respondents' reference period. Averaging over the moving reference period of the SCJS generates estimates that are most closely comparable with police recorded crime figures for the 12 months to the end of September 2009 (about six months behind the 2009/10 recorded crime figures reported in the Main Findings report). The police recorded crime statistics relate to crime recorded by the police in the financial year 2009/10;
Figure 4: Comparable crime groups
11.2 Police recorded crime
Police recorded crime statistics used in the 2009/10 SCJS Main Findings report relate to crimes committed in the financial year between April 2009 and March 2010. The figures presented in this volume were published on 07 September 2010. 87
Various adjustments were made to the recorded crime categories by Scottish Government statisticians to maximise comparability with the SCJS. In previous crime surveys in Scotland the police recorded crime statistics were adjusted further to remove crimes against victims aged 15 or younger and crimes against businesses. However, for the SCJS these adjustments have not been made for the following reasons:
- This further adjustment came from a Strathclyde police survey from 2002 which was before the change to recorded crime practices brought about by the Scottish Recorded Crime Standard so it may not be valid any longer;
- In addition, the adjustment may still be appropriate but given that the data from the SCJS can now be provided at Police Force Area ( PFA) level it is not appropriate to use Strathclyde's adjustment across all forces. Information to undertake this adjustment using local police force sources did not exist at the time of publication.
The decision not to adjust police recorded crime statistics is consistent with established practice on the British Crime Survey ( BCS).
Details of the Scottish Police Recording Standard are available from the policies section of the Association of Chief Police Officers Scotland ( ACPOS) website. 88
11.3 Comparison with the British Crime Survey
Two issues should be noted when comparing SCJS and BCS data: the different target audience for the self-completion questionnaire 89 and differences in coding crimes (section 11.3.1).
11.3.1 Coding of crimes
The coding of crimes differs between the SCJS and the BCS which reflects the different criminal justice systems in which they operate. These differences should be borne in mind when comparisons are made between SCJS and BCS estimates. One general difference is that the SCJS includes crimes where the offender is mentally ill or a police officer (these crimes are excluded in the BCS estimates).
The SCJS also differs from the BCS in that it prioritises assault over other crimes when coding offences. For example, if an incident includes both vandalism and assault, the assault component will be assumed to be more serious unless it is clear that the damage to property was the most serious aspect of the incident. This is not the case with the BCS where vandalism has priority over assault. In addition, the intent of the offender to cause harm is not taken into consideration in the SCJS and the offence code given relies only on the injuries that the victim received. The intention of the offender is taken into consideration when assigning offence codes for assaults in the BCS.
The definition of burglary in England and Wales as measured by the BCS and the definition of housebreaking in Scotland as measured by the SCJS differ in two ways:
1. The mode of entry;
In Scotland, housebreaking occurs when the offender has physically broken into the home by forced entry or come in the home through a non-standard entry point such as a window. Even if the offender pushed past someone to gain entry to the home, this would not be coded as housebreaking in Scotland. 90
Burglary measured by the BCS in England and Wales does not necessarily involve forced entry; a burglar can walk in through an open door, or gain access by deception.
2. The intention of the offender;
Burglary from a dwelling in England and Wales as measured by the BCS includes any unauthorised entry into the respondent's dwelling, no matter what incident occurs once the offender is inside. If the offender does not have the right to enter a home, but does so, this will be burglary.
In Scotland, the SCJS records the incident as housebreaking only if there is evidence of either theft from inside the home or an intention to steal in the case of attempted break-ins.