Recorded crime in Scotland: robbery 2008-2009 and 2017-2018

2. Methods

Scottish Government statisticians and Police Scotland analysts reviewed a random sample of 951 robbery crime records.

These records were sampled from two different years; 501 from 2008-09 and 450 from 2017-18. This represented 17% and 29% of all robberies recorded by the police in 2008-09 and 2017-18 respectively. The inclusion of records from an earlier year was to allow the research to identify whether any significant changes had occurred in the characteristics of robbery, as it was decreasing over the longer term.

For both years the sample was stratified by Police Scotland division. This was to ensure the prevalence of robbery across the 13 geographic areas covered by those divisions was reflected within the research.

Information was recorded about the circumstances of each robbery and the characteristics of the people involved. No personal or sensitive details were collected.

This research is based on a sample of police records (rather than all records), therefore the percentages (proportions) presented in this report are estimates. The true value may differ slightly from the findings presented below due to sampling error. As such, users should treat the following analysis as a broad indication of the characteristics of robbery, rather than as an exact measure. All figures are presented at the national level, as sample sizes are too small to provide robust estimates at geographies below this.

There are several methods of calculating an average; in this report the median is used to present the average age of victims and perpetrators (i.e. the age at which half of individuals are older and half are younger). The mean measure of average age can be more influenced by values at the upper end of the distribution (i.e. the older ages) and may not be truly representative of the average age. By taking the middle value of the data, after sorting in ascending order, the median avoids this issue and is consequently considered a better indicator of typical ‘average’ age. For the same reason, a median was used to calculate the average amount of cash stolen from victims of robbery (for those cases where any sum of money was taken)

The geographic location of each robbery in the sample was assigned to a datazone. These datazones were then compared to the Scottish Index of Multiple Deprivation ( SIMD) ^[2] , with the results included below. The SIMD is a tool for identifying concentrations of deprivation in Scotland. SIMD uses information from a range of indicators including income, employment, education, health, access to services, crime and housing to provide a measure for each of the roughly 7,000 datazones in Scotland. Each datazone is provided a rank ranging from 1 (most deprived) to 6,976 (least deprived) and based on this rank can be grouped together into deciles, with each group consisting of 10% of all datazones in Scotland i.e. the first two deciles contain the 20% most deprived datazones in Scotland.

As the sample was drawn across two years, two different editions of SIMD were used for the comparison, with SIMD12 compared to robberies from 2008-09 and SIMD16 compared to robberies from 2017-18.