I don't get it.  We have a credit card that gives us our current credit score.  It changes as much as 23 points.  Maybe more, but I'm pretty sure of the 23. 

We don't charge more than 1/2 the limit of the card ever.  I often pay off my Internet use card before I get a bill because It has a low limit.  My wife pays off her credit card every month.  We have no unpaid bills.

Yet the score bounces up and down.  Nothing in our spending changes, we do nothing different from month to month.