Key Scottish Safety Camera Programme Statistics, 2011

Methodology

Sources

1. All data relating to safety camera operations, including enforcement periods, recorded speeds at sites, and accident and injury numbers at sites, have been taken from the Scottish Safety Camera Programme database. This is an administrative data source used by all the safety camera partnerships to record data related to collisions, casualties and enforcement at all types of safety camera site operated by the partnerships. The data was extracted from the database on 31 May 2012.

2. Data relating to offences (NIP and COFPN) was compiled from audited figures supplied by the eight regional safety camera partnerships.

3. Information regarding public perception of safety cameras was taken from the Scottish Crime and Justice Survey 2010-11.

4. Respondent characteristics recorded by the 2010-11 Scottish Crime and Justice Survey (SCJS) include age, gender, the urban/rural classification of responders' homes, victim status, socio-economic group, tenure and the Scottish Index of Multiple Deprivation (SIMD) of their home. Age, gender and the urban/rural classification of the responders' homes are considered to be the most pertinent characteristics in this analysis. Analyses of other SCJS questions and data tables of all the SCJS responses are available via the Scottish Government website at: http://www.scotland.gov.uk/Topics/Statistics/Browse/Crime-Justice/Publications/publications.

Baseline data

5. With the formation of the Scottish Safety Camera Programme, partnerships have been required to collect data on road casualties at proposed camera sites for a period of 3 years prior to the start of camera enforcement. This forms the baseline against which camera effectiveness can be assessed. Due to the different enforcement periods of cameras throughout Scotland, the baseline data for all cameras do not come from the same period. For the purpose of the summary analyses on pages 3 and 4, the "baseline" annual averages refer to the baseline data collected for each camera and not to a fixed period in time. It is the sum of all the relevant baseline data divided by 3 to give an estimate of the mean annual accident/injury numbers across all safety camera sites.

6. There were no standard baseline data requirements for safety camera sites installed outwith the Scottish Safety Camera Programme. However, some baseline data were collected for some of these camera sites. With the formation of various partnerships over the last decade, many of these 'pre-programme' sites have been adopted by the programme. For the purposes of the analyses in this report only those cameras that have some measure of baseline data, and that were being enforced at the end of 2011, have been included. Cameras without the full range of baseline data have been included only in those sections relating to the measures for which data are recorded - for example, the requirement to record the number of people killed or seriously injured pre-dates the requirement to record the number of injuries of all severity.

7. No data for cameras with a baseline period later than 2006-2008 have been included in these figures. This is to ensure that the baseline does not overlap with the latest 3-year period measured, as this would lead to figures being counted twice. Only cameras with at least 3 full years' post-baseline data have been included (ie: no cameras with an enforcement commencement date later than 31 December 2008).

8. Prior to publication all data undergoes quality assurance by the relevant local authorities, however due to operational restrictions in some instances this has not been completed. In line with our policy, any minor revisions will be highlighted in next year's publication. If there are significant revisions to the data the current bulletin will be reissued at a later date.

9. The "latest" annual averages refer to the data collected for the fixed 3-year period of 1 January 2009 to 31 December 2011 inclusive. This is the latest period for which three full calendar years' data is available. The data is added together and divided by 3 to provide an estimate of the current mean annual accident/injury numbers across all safety camera sites.

Public perceptions

10. The chi-square test was used to test for significant differences between respondent groups. The p-values for all tests are shown in the tables at Annex B.

Revisions

11. Some of the data used in this bulletin differs slightly from that used in Key Scottish Safety Camera Programme Statistics 2010. This is a result of additional quality checks being carried out on the data leading to adjustment (eg: corrections made to the grid references attached to incident locations may move them in or out of camera sites), and/or reclassification of some incidents (eg: serious injuries later proving fatal). A summary of the changes is provided in Annex C.