"Buckets" are not determined primarily by your age of credit history.
What scoring algorithm you are placed in is a branching tree, of which length of credit is not the trunk.
The trunk are the major factors, namely pyment history and current util.
There are two major factos that Fair Isaac has identified as the major factors in generation of your credit score.
First, at 35% of total score, is payment history.
Second, at 30% of total score, is util of existing credit.
Third, fouth, and fifth in the tree of credit bracketind are lenghth of credit (15%), new inquiries (10%) and credit mix (10%)
How FICO determines what agorithm, or "bucket," you are placed in is not published by them. But is is not totally transparent.
Common sense, and other published literature (see U.S. Patent No. 6,202,053) leads to the conclusion that their first branch of the tree is based your current payment history (lack or presence of any major derog)
On that branch will spread twigs that lead to further sub-algorithms based on % util. and then sub-sub branches based on length of credit, and so on.
If you have a major derog, then other main branch algortihms may be used to create branches that then consider, in order of FICO scoring prioritiy, payment history, length of credit, and then the minor categories of inquireis and credit mix.
If you don have a major derog,that may pass you onto a different major branch, based primarily on util of existing credit, but then "twgging out" for various credit lentdths, inquires, and credit min.
So on and so on,.
When yiou add all of the most likely branches and subbrances up, it totals about 12 possibilities.
Each has its own scoring algorithm, which asseses the risk, under those conditions, and comparison with other consumers in that same bucket, of your predicted fisk for future default. It is different for each of these scoring algorithms, or "buckets."
