Although we combine with internal scoring and manual review, as stated; If I was using MaxMind exclusively I'd consider 5.0 to 7.5 a good indicator of a possible fraudulent order.
This is based on their current riskScore system[1] (changing on January 1st, 2014) and 10 as an instant failure without review. Most orders will generate a non-0 score, however.
Another great tactic for preventing fraud is to never indicate an order has failed or a card hasn't been charged ('ghosting'), this is a tactic used heavily by Google for AdWords and other paid services.
Giving a clear indication of failure allows "carders" a way to easily figure out your detection algorithms by placing orders until one gets through, and share that information with others who will attempt to victimize your checkout process.
riskScore is a combonation of hard coded scoring, along with what I'd equate to a bayesian filter.
In a way, riskScore simplifies the calculation, because it's a percentage instead of an arbitrary number. Depending on your business, I would consider starting at 30% for manual review, and 90%+ for auto refusal, making adjustments to the threshold from there.
This is based on their current riskScore system[1] (changing on January 1st, 2014) and 10 as an instant failure without review. Most orders will generate a non-0 score, however.
Another great tactic for preventing fraud is to never indicate an order has failed or a card hasn't been charged ('ghosting'), this is a tactic used heavily by Google for AdWords and other paid services.
Giving a clear indication of failure allows "carders" a way to easily figure out your detection algorithms by placing orders until one gets through, and share that information with others who will attempt to victimize your checkout process.
[1] http://www.maxmind.com/en/ccfd_formula