How is the Rarity Index calculated?
Something rare is something available with difficulty. Although the number of plushes originally produced for each character has something to do with rarity, it is not the complete story.
There is no universally accepted index for rarity, hence a custom one has been defined here. There could be many other ways to define such an index that would be at least as good as what we have done. We nonetheless propose this one to the community of fans, and pledge to update it monthly.
Since scales from 1 to 10 are popular, we used this principle and started each character with a perfect 10. The index gets reduced as follows:
• Every time a sale of a plush is reported in the past 3 years, the index drops by 50/[sale price].
• Every time an add is placed in the past 6 months, the index drops by 25/[advertised price] if it is ebay, and 15/[advertised price] elsewhere. A listing on ebay drops the index further than any other place because of its prominent position hence increases the availability. An ad that remains on for more than a month will drop the index every month.
These factors have been empirically determined to keep the index between 1 to 10 for all the characters. They will change if needed in the future.
If documented sales are reported to the administrator of the forum, they will be taken into account starting with the next monthly index update.
We hope you will find this index to be interesting and useful.