A common claim with a specific evidence base
“Cameras deter crime” is repeated in almost every security product page. The strongest evidence behind it comes from a systematic review and meta-analysis by Eric Piza, Brandon Welsh, David Farrington and Amanda Thomas, published in Criminology & Public Policy in 2019 and covering 40 years of evaluations. It is the source used here. Reading it carefully shows what the research supports and, just as usefully, what it does not.
What the review found overall
The authors located 80 distinct evaluations, of which 76 provided the data for the pooled analysis. Follow-up periods averaged about 17.5 months. Pooling the results, they found CCTV was associated with a significant but modest decrease in crime: approximately 13 per cent lower in CCTV areas compared with comparison areas. They describe the effect as modest, and that is a fair way to read it.
The largest and most consistent effects were in car parks. Other settings showed significant reductions too, particularly residential areas, but the strength of the effect varied by setting and by the way the analysis was done.
The residential findings, and their limits
For residential areas the review included 16 evaluations, and only five of those individually reported statistically significant reductions. Pooled together, the residential effect was about 12 per cent lower crime in the treated areas, and it was statistically significant. But the authors report that when they used the smallest effect from each study rather than the largest, the residential result was not significant. In other words, the finding leans on which measurement you take, and the authors present those analyses side by side.
A definition in the paper matters here. In its terms, residential CCTV schemes are schemes covering public areas such as streets in residential neighbourhoods. These are area-wide systems evaluated by researchers, not a camera on one household’s front door. The review does not report on doorbell cameras or single-home systems, so it cannot tell a homeowner what a single camera will do for their address. The review is also international rather than specific to England and Wales, Scotland or Northern Ireland, and it notes that residential schemes made up 5.9 per cent of the UK evaluations compared with 45.8 per cent of the US ones.
What made the schemes work better
Two features stand out. Schemes with active monitoring, where someone watches or responds, produced larger effects than passive systems that merely record. And schemes that combined CCTV with other interventions produced larger effects than schemes using few or no other measures. The authors’ policy conclusion is that CCTV should be narrowly targeted on vehicle and property crime and not used as a stand-alone measure.
For a homeowner, that maps onto a familiar principle: a camera is one layer. Lighting, secure locks and someone who notices and acts on alerts are likely to matter alongside it, though the review itself does not test that specific combination in homes.
How confident can we be?
The authors are open about the design limits. With one exception, a single randomised experiment, every included study was a conventional quasi-experiment comparing crime before and after in treated and comparable areas. That design is weaker than randomisation. They also tested for publication bias and concluded it did not affect their results, and they looked at displacement, where crime simply moves elsewhere. In the residential studies that tested it, 11 in all, four found evidence of a diffusion of benefits, meaning nearby areas also saw less crime, and one found both diffusion and displacement. The rest found neither.
Even the headline number needs humility. A 13 per cent average reduction across places and schemes is a reasonable summary, but it does not mean any individual camera cuts a household’s risk by that amount.
Reading marketing claims sensibly
When a brand says cameras “deter” burglars, the fair reading is that area-wide, well-targeted and ideally monitored systems have been linked to modest crime reductions. That is not the same as proof that a dummy camera, a single unmonitored doorbell, or a sticker does anything at all, and this review does not address those products. The authors’ own advice is that CCTV should not be deployed as a stand-alone measure. Treat cameras as evidence-gathering and detection tools first, and any deterrent effect as a possible bonus.
The bottom line
The best-known research review found CCTV associated with a modest overall fall in crime of around 13 per cent, largest in car parks and significant in residential areas when taken as a pooled result, with stronger effects where schemes were actively monitored and combined with other measures. But the evidence comes mostly from area-wide schemes and weaker before-and-after designs, and it does not test individual home cameras. Buy a camera for the footage and alerts it gives you, not because a study proves it will stop burglars.