cise. One of the few controlled studies
to date was carried out in the clothing
retail shops in 19991:
The ˲ purpose of installing the systems
was clearly defined: reduce the stock
losses through customer and staff theft.
The ˲ measures for stock losses were
clearly defined: the number and value
of stock losses was monitored, and
any reduction of losses calculated as a
percentage of sales profits during the
same period.
Stock losses were measured four ˲
times—twice during a six-month period before and after the introduction
of CCTV.
The ˲ efficiency was calculated in
terms of how many years the system
would have to operate at the observed
level of effectiveness to recover its investment.
During the one-year period, they ˲
monitored for a number of side effects
such as footfall, overall sales, customer
assessment of shops, and so forth.
This illustrates that carrying out a
meaningful assessment under controlled conditions requires significant
resources and domain expertise, even
for a conceptually simple study: the
assessment was focused on a single
crime, the monitoring environment
was constant, and systems for measuring the impact were already in place.
The results showed that stock losses
were reduced significantly in the first
three months of CCTV introduction—
but then rose again. After six months,
the average loss reduction was a near-insignificant £ 4—at an average capital expenditure of £ 12,000 per CCTV
system, it would take 58 years to recoup the capital cost. In the end, only
shops selling high-value fashion using
high-end CCTV systems reduced stock
Paso Times6 reported in January 2009
that the program was not effective
because only a dozen incidents had
been reported. A spokesperson for the
Governor of Texas responded that the
problem was not with the technology,
but the way its effectiveness was assessed. It may look like a weak argument, but it points to the key problem:
How do you assess effectiveness of a security technology such as CCTV? How
can you determine whether the results
represent value for the money spent on
technology, or privacy invasions that
occur because of its existence?
The answer is conceptually simple:
effectiveness of a particular deployment means that it achieves its stated
purpose; efficiency means the desired
results are worth more than the resources required to achieve them. But
the execution of a study to measure
them is a challenging and costly exer-
the sports advertising industry” to search
footage for suspects and incidents.
Since that technology is not quite ready,
London police publish images of sus-
pects on the Internet and ask the pub-
lic for help. Recruitment of untrained
members of the public to assist in CC TV
monitoring is a growing trend:
In a London housing project, resi- ˲
dents have been given access to CCTV
cameras, books of photos of individu-
als who had been warned not to tres-
pass on the estate, and a phone num-
ber to call if they spotted any of them.
In the tourist town of Stratford-on- ˲
Avon, residents and business can con-
nect their own CCTV cameras to an In-
ternet portal, and and volunteers who
spot and report crimes can win prizes
of up to £ 1,000.a
Approximately $2 million has been ˲
spent on Webcams for virtual border
surveillance at the Texas-Mexico bor-
der, enabling virtual local residents to
spot and report illegal immigration.
The involvement of untrained members of the public in surveillance harbors many potential risks to privacy,
public order, and public safety (e.g,
vigilantism) that must be identified and
considered. But even leaving those concerns aside, early indications from the
last project suggest this not a quick fix
to make CCTV more effective. The El
a Details of the rewards were revealed last December; see http://news.bbc.co.uk/1/hi/tech-
nology/ 8393602.stm