Fourteen Cameras, a Rise in Recorded Theft and a Neighbouring Council
After a well-publicised mugging, a Maltese local council installs 14 CCTV cameras in its main square and two side streets at a cost of €80,000, funded by a national scheme. At the end of the first year the district police inspector reports that recorded thefts in the area rose from 55 to 77, and that shoplifting reports from the three square-side shops had 'more than doubled'. The council's press release claims the cameras 'have exposed a crime wave'. A resident writes to the newspaper saying she now reports every stolen item because she believes the cameras make it worthwhile, whereas before she 'didn't bother'. Meanwhile the neighbouring council, which installed no cameras, saw recorded thefts rise from 60 to 71. The council must decide whether to extend the scheme and what to tell residents.
1. Explain why the rise in recorded theft does not establish a rise in theft.
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Official statistics record reports and decisions to record, not offences. They pass through several filters: whether a victim notices, whether they define it as a crime worth reporting, whether they report it, and whether the police record it. A change at any filter changes the count without any change in offending. The resident's letter is exactly this mechanism: she now reports because she believes reporting is worthwhile. Publicity around the cameras plausibly raised both reporting and recording.
The numbers are small and the comparison area also rose. 55 to 77 is 22 extra incidents in a small area; 60 to 71 in the neighbouring council, with no cameras, is an 18 per cent rise. Something general was happening, so the cameras are not needed to explain the local rise. On 'shoplifting more than doubled', the base is unspecified: 6 to 14 is a striking percentage and a trivial number.
Displacement is not measured. Cameras in the square and two streets may move offending elsewhere in the district, which would appear as an increase in area totals while the square itself is safer. No buffer-zone measure is reported.
Conclusion: the press release confuses recorded crime with crime. A victimisation survey or a controlled before-after comparison is required before any claim about the scheme's effect.
2. The council wants to know whether the cameras worked. Design an evaluation and justify each element.
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Outcome measures, stated in advance. Recorded theft and robbery in the intervention area per 1,000 residents and per retail outlet; the same counts in a buffer zone around the cameras to detect displacement; and residents' fear of crime and their reported avoidance of the square. Fear is a legitimate separate outcome: cameras may reduce it without affecting crime, and a scheme cannot be judged on one measure alone.
Comparison area. The neighbouring council without cameras, matched on population, retail density and deprivation, controls for national and regional trends - which we already know moved upwards there.
Before-and-after with an adequate baseline. At least two years of pre-installation data and two post, so that random fluctuation in small numbers is visible; 22 extra incidents across a single year is consistent with ordinary noise.
Victimisation survey before and after, using identical questions, because official counts are confounded by reporting. This is the element that answers the resident's point directly.
Limits. Assignment was not random, the installation was publicised, and the comparison area may have had its own policing changes. The evaluation should present its findings as the scheme's best estimate, not proof.