After several years of development, I have just rolled out a new rarity system for railroad stocks and bonds. You may see it in action by searching for any certificate in your collection.

After many conversations with dealers, collectors and authors, I decided to use a 7-point system arrayed from most common to most rare.

The system is arranged like this:

R1 = likely to appear more than 10 times per year
R2 = likely to appear 4 to 10 times per year
R3 = likely to appear 1 to 4 times per year
R4 = likely to appear once every 1 to 3 years
R5 = likely to appear once every 3 to 5 years
R6 = likely to appear once every 5 to 10 years
R7 = likely to appear less than once every 10 years

R? = Rarity unknown. I reserve this designation for certificates priced under $50 which are suspected of being substantially scarcer than their prices would otherwise indicate. For instance, I would use this designation in the case where a certificate has been seen only once or twice in 30 years, but it sold for only $15. Why so cheap? Is there an unreported hoard somewhere? Was the $15 sales price a very lucky fluke for some collector?

The system does not measure populations. We can NEVER know the numbers of certificates that exist. Instead, the system measures historic appearances over the last thirty years. It gives you hints on rarity by estimating how often certificates come up for sale. The system is database-driven, so rarity estimates represent appearances as recently as the last database upload. There are currently about 980,000 appearances in the database.

See http://www.coxrail.com/Rarity.htm for a further discussion of the system and its accepted shortcomings.