Following the methodology employed at the Institute of Criminology (Cambridge University), the mean scores of the survey responses from Prison Officers were calculated for each prison, for each question in the survey. These mean scores were then broken down into quartiles. Those prisons appearing in the worst performing quartile were marked with a red indicator. The survey questions were then separated into those questions that focused on 'safety' issues (such as 'do you feel safe in prison?') and those questions which dealt with non-safety issues (such as 'are you satisfied with your career prospects?')38. We then totalled the number of red indicators for each prison for each of the two categories. Those prisons appearing in the 'worst performing' quartile for each category were then marked with a red indicator in our traffic light matrix.
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38 We grouped four questions in the Prison Officer survey together to produce one joint result. These four questions were concerned with line management issues and we felt they were too similar to warrant being included four times in the traffic light analysis.