DM: Credit Score

[Musial Jerry]

Hi,
        I am looking for help/resources related to credit scoring of
'existing' customers.  In particular, I am interested in how 
researchers
deal with tenure as it relates to whether or not one of our customers 
will
continue to pay their bills in a timely manner.  We intuitively feel 
that
the longer a customer has been with us (and paying us) the better 
credit
risk.  However, my initial results show that the longer a person has 
been
with us, the odds of his not paying increase.  Anyone have any ideas?

Thanks
Jerry Musial
BellSouth Cellular