Channel 4 Television are
using advanced optimization technology based on genetic algorithms
"The whole area cries out for advanced software technologies.
But it is not an area that you can just jump into."
That is how Stephen Ottner, Systems Manager at Channel 4 summarises
the information technology perspective on the management of commercial
airtime. With the ability to encapsulate existing constraints and
accommodate new constraints, it is possible for knowledge-based
systems to keep pace with a fast-changing market and with the developing
nature of a TV company. It is a business wrapped up in a mystique
and with a language all of its own - and one where skills and experience
are highly valued. For Channel 4, sequencing of commercial breaks
(a process that used to be undertaken manually) provided a logical
starting point for the use of AI technology: "It was a bounded
project, involving a limited number of users and limited risk, but
with significant potential gains," comments Stephen Ottner.
From January 1993, Channel 4 has been a statutory corporation
responsible for its own financial future, dependent on advertising
revenue for 96% of its revenue - and responsible for selling its
own airtime (a responsibility that had previously been given to
the regional ITV companies).
During the day, Channel 4's strength is the housewife market whilst
in the evenings Channel 4's strength lies in its varied targeting
ability. In comparison with ITV, Channel 4 audiences contain a greater
proportion of younger, lighter, up-market, male viewers (audience
research has also identified Channel 4's ability to target cluster
groups defined by names such as "Progressive Priscillas"
and "Free-thinking Franks"). Unlike the ITV companies,
Channel 4 also promotes the fact that it is able to give advertisers
access to a UK network of all the ITV regions - booked from a single
point. At the same time, regional advertisers can choose to buy
Channel 4's six so-called "macro-regions" (which correspond
with the existing ITV regions) separately. The combination of two
to five regions is known as a "Super-macro" and provides
advertisers considerable flexibility in placing advertising copy.
Sequencing of commercials within each break has presented Channel
4 with something of a headache - ensuring that spots on different
regions go out simultaneously whilst satisfying as many of the advertisers"
requests for special positions as possible: "Advertisers are
buying audience, not airtime," comments Stephen Ottner. "It
is a complex trading commodity." Although, in theory, a five
minute break could contain 180 spots across all regions, in practice
the maximum scheduled break is four minutes with 50 spots. Selling
of this volatile medium is only closed off half a day in advance
of transmission time, at which point the breaks need to be sequenced.
At the beginning of 1993, it was estimated that around 20% of
advertising would be sold regionally. In fact, the figure is nearer
40%, half of which is made up of Super-macros. Advertisers may also
specify to have commercials placed first in the break, last in the
break or "Top & Tail" in a break -making break sequencing
a challenge if optimal use of airtime is to be achieved. Definition
of a knowledge-based system to solve the problem requires observation
of a number of prioritised "rules": Top of the list is
the need for no overlaps or gaps, with Top and Tail or First and
Last network spots also receiving high priority. Lower down the
list are First and Last Super-macro spots and non-reporting Super-macros
sequenced to play at the same time.
Stephen Ottner chose to use "XpertRule", a respected
knowledge-based system generator from Lancashire-based XpertRule Software
Limited: "Conventional programming could not cope with the
need for additions and changes and simply putting a graphical front-end
on the mainframe sales system would still leave the option for manual
manipulation."
A downloaded flat file from the mainframe-based airtime sales
system ("SAMS") passes an unordered list of spots in the
break to the XpertRule Break Sequencer which uses "Genetic
Algorithm" optimization to ensure that all constraints are
complied with before the ordered information is passed back to SAMS.
Software Development Director at XpertRule Software, Eric White, comments:
"Optimization problems can be solved by iterative trial and
error. But, as the number of possible combinations grows it becomes
impractical to try all combinations to arrive at a solution in a
reasonable time. Rule of thumb can be used to narrow down the options
but, in most cases, good rules are not available or are difficult
to capture." He adds: "Numerical optimization techniques
are currently available in most advanced spreadsheets, but these
tend to be incapable of optimizing problems involving sequencing
or scheduling and they are "exploitation" rather than
"exploration" techniques. They also fail to cope with
outcomes that involve subjective assessment by an expert."
The solution used by XpertRule involved the use of genetic algorithm
techniques which allows the exploration of large search spaces for
optimal or near optimal solutions. Random creation and regeneration
of "Chromosomes" (solutions) and the mixing of "Genes"
(parameters) allows a process of natural selection to create Chromosomes
that have the greatest "fitness to survive" - a solution.
Trading off time taken to reach the solution and the quality of
that solution allows a "good" solution to be reached within
a short time, as opposed to an optimal solution that might require
infinite time.
Stephen Ottner comments on the fact that the initial specification
for the Break Sequencer was contained within half a dozen sheets
of A4 paper: "XpertRule Software have asked us what we needed,
rather than tying us down to an all-embracing detailed specification.
It is an approach that has allowed scope for change and discovery.
Development has been an iterative process. In spite of the apparent
mystique surrounding TV airtime, they quickly understood the business
requirements and produced a workable solution without having come
down here - they were good at getting to the heart of the matter."
Discussions started in January 1993 and the target of one month
for completion of the first phase of the project was actually bettered
by XpertRule Software. One of the factors that attracted Channel 4 to
XpertRule Software was the ability of XpertRule to run on PCs and under
Microsoft Windows - two technologies that formed part of Channel
4's IT strategy. XpertRule Software has also been able to incorporate
PC graphics to simulate the graphical representation that users
sketched when explaining how a break was built up - listing the
regions along a horizontal axis and with time running vertically
down the screen.
Stephen Ottner believes the fact that it has been possible to
extract and return the existing mainframe data into and from the
knowledge-based system has helped to build up confidence in using
a system designed to take over much of the drudgery involved in
break sequencing: "The team is now totally sold on the idea.
Two or three people used to be wholly committed to sequencing work,
whereas now it only requires one or two. It is an important motivation
since the work is now manageable with the number of people available
- they are not working just above the waterline." Stephen Ottner
stresses that none of the progress with XpertRule does away with
the expertise of the staff. Indeed, one of the most recent enhancements
to the system has been the addition of a facility that permits manual
override: "There are many soft constraints that cannot be built
into the system: Being sensitive to the positioning of products
within a break; dealing with agencies and coping with necessarily
detailed arrangements - simply making sure that there are no cock-ups.
Looking at breaks is still important."
Stephen Ottner acknowledges that there was initially some scepticism
about the ability of a relatively small software house from Leigh
in Lancashire to get to grips with the needs of a major TV company
based in the heart of the West End. At present Channel 4 is planning
to involve XpertRule Software in a much larger* project involving its
advanced software technologies for a part of airtime management
of much greater strategic importance than break sequencing. Implementation
of the first project has been an important testbed for Channel 4
and has required an understanding of the role of human expertise
as much as that of a knowledge-based system. Stephen Ottner summarises
the benefits that are universally accepted: "Instead of simply
managing breaks, we are able to find better options for the use
of airtime. As far as we know, no other TV company does anything
like this."
*(editor's note: The "larger" project went ahead to
completion in 1995, but no information is publicly available)
Gerard Liston, Leeds - October 1993
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