Annex 5: Comparison between the SCJS and police recorded crime statistics
A5.1 SCJS comparable 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 ( chapter 1). Police recorded crime is a measure of those crimes reported to the police (estimated by the SCJS to be 42% of comparable crime) and then recorded by them as a crime or offence.
In order to compare the crime rates measured by the SCJS and police recorded crime, a comparable subset of crimes was created for a set of crimes that are covered by both measures. 70% 135 of SCJS crime as measured by the SCJS 2008/09 falls into categories that can be compared with crimes recorded by the police.
It is possible to make comparisons between the SCJS and police recorded crime statistics for six general offence groups: vandalism, housebreaking, theft of motor vehicles, bicycle theft, assault and robbery ( annex 3). Due to the small numbers of these crimes reported in the SCJS these have been grouped into Vandalism, Acquisitive (including housebreaking, bicycle theft and theft of motor vehicles) and Violence ( annex 3).
SCJS crime estimates are based on interviews conducted between April 2008 and March 2009. Interviews have been conducted continuously with respondents being asked about crimes they have experienced in the 12 months prior to the interview. The moving reference period used in SCJS means that the data collected centres around March 2008 and is most closely comparable to a period ending September 2008, six months ahead of the police recorded crime data reported here ( annex 3).
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) 2008 population estimates of households and adults ( annex 3).
Figure A5.1: Comparable crime groups
A5.2 Police recorded crime
Police recorded crime data relate to crimes committed between April 2007 and March 2008. 136 The figures presented in this volume are those as notified to the Scottish Government and that were contained on the database on 09 June 2009.
Various adjustments were made to the recorded crime categories to maximise comparability with the SCJS. In previous crime surveys in Scotland the police recorded crime figures were adjusted further to remove crimes against victims aged 15 or younger and crimes against businesses. In the SCJS 2008/09 the adjustments have not been made for the following reasons:
- This further adjustment came from a Strathclyde police survey from 2002/03 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 is consistent with established practice on British Crime Survey ( BCS).