The burglar stat that was never about cameras

Camera marketing leans on a small set of statistics, repeated from page to page until nobody remembers where they started. Two of them do most of the work: "60% of burglars will choose another target," and "83% of burglars check first." A third, newer one says homes with visible cameras are "300 percent less likely" to be targeted.

I went back to the sources. The first two come from one study, and both are about alarms. The third I could not trace to any paper, and as written it can't be true.

Where the 60% comes from

In December 2012, researchers at the University of North Carolina at Charlotte published Understanding Decisions to Burglarize from the Offender's Perspective, by Kristie Blevins, Joseph Kuhns and Seungmug Lee. They surveyed 422 incarcerated burglars in North Carolina, Kentucky and Ohio about how they chose targets and what put them off. It's a genuinely useful study, and it is the origin of both famous numbers. Here is the passage, from the report itself:

In a separate question later in the survey, we asked respondents if alarms in particular dissuaded them from burglarizing a particular establishment. About 60% of the burglars indicated that an alarm would cause them to seek an alternative target. In addition, about 83% of offenders would attempt to determine if an alarm was present before attempting a burglary.

"Alarms in particular." The report's own table gives the count: 255 of the 422 respondents, 60.4%, said an alarm made a difference in target selection. The 83% is about checking for an alarm. Neither question was about cameras.

Now compare how it gets retold. Security.org's camera page answers "Are cameras a good crime deterrent?" with this: "Cameras are a good crime deterrent, as 60 percent of most burglars will choose another target if they find alarms or cameras." The drift is one word, but it is enough: a finding about alarms is now selling cameras.

What the same survey said about cameras

The survey did ask about cameras, in a different question. Burglars were asked which of a set of factors would cause them to avoid a target. The report plots the answers in a bar chart (its Figure 4, 360 respondents). Read off that chart, cameras and surveillance equipment land at a little over 40%. Ahead of them: people inside the home (about 60%), a police officer nearby (about 55%), noise inside, an alarm, and seeing neighbours.

So cameras do matter to burglars, by their own account. Roughly four in ten said a camera would make them avoid a place. That's a real deterrent. It just isn't the headline number, and it ranks below the plain fact of someone being home.

The report's text also says that alarms and outdoor cameras "were considered by a majority of burglars" when choosing a target. Considered is not the same as deterred, and that distinction is exactly where the marketing gets sloppy.

Three limits the study states or implies

• These are burglars who got caught. The sample is incarcerated offenders. People who were never arrested may choose targets differently, and the survey can't speak for them.
• It's self-report, with a 28% response rate. The authors surveyed 422 of a sampling frame of 1,513 and note the rate is "somewhat low" but typical for prison studies. What someone says they would do on a questionnaire isn't a record of what they did.
• It was funded by the alarm industry. The university's 2013 announcement of the study says funding came from the Alarm Industry Research and Educational Foundation, under the Electronic Security Association. That doesn't make the findings wrong, and the authors reported plainly. It's the context a reader should have.

The "300 percent" number

SafeWise's page on camera deterrence says: "A study published in the Journal of Quantitative Criminology found that homes with visible cameras were 300 percent less likely to be targeted compared to similar homes without them." I searched for that study and could not find a paper that reports this figure. I'm not saying no such paper exists; I'm saying I couldn't locate it, so I can't tell you what it measured.

I can tell you the phrase is broken arithmetic. A risk can fall by at most 100%, which means to zero. "300 percent less likely" usually means someone took a finding like "unprotected homes were targeted three or four times as often" and flipped it the wrong way. That may or may not be what happened here. Either way, the number as printed isn't a measurement.

What the strongest evidence says

For a real answer, go to the meta-analyses. The largest is Eric Piza, Brandon Welsh, David Farrington and Amanda Thomas, "CCTV surveillance for crime prevention: A 40-year systematic review with meta-analysis," published in Criminology & Public Policy in 2019. It pools four decades of evaluations of CCTV schemes. Its research summary is short, and I'll quote the core of it:

The findings show that CCTV is associated with a significant and modest decrease in crime. The largest and most consistent effects of CCTV were observed in car parks. The results of the analysis also demonstrated evidence of significant crime reductions within other settings, particularly residential areas. CCTV schemes incorporating active monitoring generated larger effect sizes than did passive systems.

And from its policy implications, the line I'd put on every camera box:

Of particular salience is the continued need for CCTV to be narrowly targeted on vehicle crimes and property crime and not be deployed as a "stand-alone" crime prevention measure.

Three things fall out of that. The effect is real but modest. It is larger when a person is actively watching than when cameras only record. And it is larger when cameras are combined with other measures than when they work alone. The paper evaluates CCTV schemes in settings such as car parks and residential areas, which is a different unit from one homeowner's doorbell camera, so treat it as the best available direction rather than a number for your house.

Why this beat cares

I help design the AI security systems for a veteran-owned (SDVOSB) home-security company run by fellow veterans. I do not own that company and earn nothing from this link. Full policy here.

The honest version of the evidence is also the useful one for design. Every finding above points the same way: a camera nobody is watching is mostly a recorder, and a recorder tells you what happened after it happened. What changes the odds is the chain behind the camera. Someone, or something, notices in time, and a response follows. In EW work, a sensor feed nobody is watching is a log, not protection. The burglars in this survey said much the same thing: the deterrents they ranked highest were signs that a person was present or on the way.

What to do with this

• Treat quoted percentages as claims until you see the question. Ask what the respondents were asked, and whether the number is about cameras, alarms, or "security" in general.
• Don't buy cameras as a stand-alone. The review's own recommendation is to combine them with other measures. Lighting, alarms, locks and a response plan belong in the same design.
• Decide who watches. The evidence favours active monitoring. Whether that is a monitoring service, verified alerts to your phone, or on-site staff, make it someone's job.
• Make presence visible. People inside and nearby topped the burglars' own list. Occupancy cues and neighbours still do work that no camera does alone.

What I could not confirm

The camera percentage is read off a chart. The UNC Charlotte report gives the camera result only as a bar in Figure 4, without a printed number. "A little over 40%," "about 60%" for people inside and "about 55%" for an officer nearby are my readings of that chart.

I worked from the meta-analysis summary, not the full paper. The full text of Piza and colleagues was not openly accessible to me. Everything I report from it comes from the authors' published research summary and policy implications, quoted verbatim above. I have not cited its pooled effect sizes, setting-by-setting numbers, or any figure for passive systems beyond what the summary says, because I could not read them myself.

The "300 percent" study. As noted, I could not find it. If a reader can point me to the paper, I'll correct this report in place.

Nothing here evaluates or recommends any camera, alarm, monitoring service or installer.

The signal

The most famous burglar statistic in camera marketing is an alarm statistic. The same survey says cameras deter too, for roughly four in ten burglars, and less than the simple presence of a person. The best evidence on CCTV finds a modest effect, larger with active monitoring and in combination with other measures, and its authors warn against using cameras alone. That's a less exciting sales line than 60%. It's also the one that tells you how to build a system that works.