Berry

Link Analysis 337
There are many approaches to defining the target set of customers. The company
could effectively use neighborhood demographics, household surveys,
estimates of computer ownership by zip code, and similar data. Although this
data improves the definition of a market segment, it is still far from identifying
individual customers with particular needs. A team, including one of the
authors, suggested that the ability to find residential fax machine usage would
improve this marketing effort, since fax machines are often (but not always)
used for business purposes. Knowing who uses a fax machine would help target
the work-at-home package to a very well-defined market segment, and
this segment should have a better response rate than a segment defined by less
precise segmentation techniques based on statistical properties.
Customers with fax machines offer other opportunities as well. Customers
that are sending and receiving faxes should have at least two lines—if they
only have one, there is an opportunity to sell them a second line. To provide
better customer service, the customers who use faxes on a line with call waiting
should know how to turn off call waiting to avoid annoying interruptions
on fax transmissions. There are other possibilities as well: perhaps owners of
fax machines would prefer receiving their monthly bills by fax instead of by
mail, saving both postage and printing costs. In short, being able to identify
who is sending or receiving faxes from home is valuable information that provides
opportunities for increasing revenues, reducing costs, and increasing
customer satisfaction.
The Data as a Graph
The raw data used for this analysis was composed of selected fields from the
call detail data fed into the billing system to generate monthly bills. Each
record contains 80 bytes of data, with information such as:
■■
■■
■■
■■
■■
■■
■■
The 10-digit telephone number that originated the call, three digits for
the area code, three digits for the exchange, and four digits for the line
The 10-digit telephone number of the line where the call terminated
The 10-digit telephone number of the line being billed for the call
The date and time of the call
The duration of the call
The day of the week when the call was placed
Whether the call was placed at a pay phone
In the graph in Figure 10.8, the data has been narrowed to just three fields:
duration, originating number, and terminating number. The telephone numbers
are the nodes of the graph, and the calls themselves are the edges, weighted by
the duration of the calls. A sample of telephone calls is shown in Table 10.1.