I just read an article about Q David Bowers concept of a universal rarity scale. The impression implies that it has been around for a little while, but this was my first exposure to it. It encompasses all U.S. coins, from first struck to the latest mass productions of the mint. It allows all collectors to have a common ground to compare coins. Would this help TPG's and collectors a like? I think so, but I would be interested to hear different opinions. The down side would be the replacement of the Sheldon Grading Scale, which Bowers feels is antiquated. What do we do then with our present slabbed coins?
The URS proposed by Bowers, which I first read about in the mid-1990s, and the Sheldon-based grading scale do not refer to the same things.
Tom is correct, rarity scale and grading scale are completely different. Bowers' concept of a Universal Rarity Scale is about the quantity, not quality, of the coins. Sheldon developed a Quantitative Scale for Condition for the grading of Large cents in 1949. By 1953 the original scale was outdated. In the 1970's the ANA decided to adopt the scale for use on all coins. That is how we got the grading system in use now.
If I remember correctly, the Sheldon scale arose from his observtion that the poorest condition penny, albeit still identifiable, was worth 1/70th that of a "perfect" one. Of course, that ratio hardly holds true for every denomintion and issue, but we still have that 1 to 70 score in use for all coinage, and I suppose it works well enough. It's certainly entrenched. One problem with any universal rarity scale is that it's hard to take into account the impact of where you're collecting on that factor. Also, at the high end, many uncommon coins in the highest grade are locked up in collections, which renders their effective rarity much higher. That's just one aspect of the whole issue of condition rarity, which can get complicated.
There are two kinds of rarity - absolute rarity and conditional rarity. Absolute rarity applies the total number of coins of a given type that are know to exist. Conditional rarity applies to the number of coins known to exist in a given grade. The URS deals with absolute rarity. The population reports of the TPGs, (and to a lesser degree combined with the known census of raw examples), deal with conditional rarity. Neither of these numbers has anything to do with known mintage numbers and mintage numbers do not have any bearing on the absolute rarity of a given coin. The only thing that determines absolute rarity is the number of coins known to still exist. And the number known to still exist is never, or almost never, a factual or hard number. Rather the number is stated as a range such as 250 to 500 for example. And that number is determined by documented market records over a long period of time. So, in other words a given coin may be known to have had a mintage of 2 million coins, but in the present day there are only 250 to 500 known examples of that given coin that still exist. That's why mintage doesn't matter. Conditional rarity on the other hand may matter, or not matter. For example there may only be 25 examples of a given coin in MS64. But there may be hundreds of thousands of examples graded lower than that, and thousands graded higher than that. Which if the case the coin obviously is not conditionally rare. But, if the coin is graded MS64 and there are only 3 graded higher the the coin is conditionally rare. So conditional rarity may or may not matter. It is also important to realize that population numbers are not hard numbers either, they are only estimates. The few studies done on population numbers indicate that they may be off by as much as 20%, and in some case more, others less. And sometimes a coin can be conditionally rare and absolutely rare at the same time. But as a collector we must always know the difference and always be aware of it. For rarity, combined with condition (grade) and popularity is what determines the value of any given coin. And it is also very important for collectors to realize that popularity is very often the single most important factor there is when it comes to determining the value of a given coin. For a coin may not be absolutely rare by any description, nor be conditionally rare by any description, and yet because that coin has tremendous popularity it is still very valuable in dollar terms. Bottom line absolute rarity usually trumps conditional rarity. But popularity can trump them both. Combine all three in one coin and you have something that few will ever be able to afford. edit - Forgot to mention that there are many different rarity scales that are used when describing different kinds of coins or even tokens. The URS is typically only applied when talking about US coins for example. Some rarity scales only apply the the coins of a given country, or a certain type of coin from that given country. But not all coin types even have a rarity scale because no one took the time to study them well enough to develop one.
The problem with Bower's URS is that it really ISN'T an improvement over the Sheldon Rarity Scale. The Sheldon scale has 8 levels with 8 being the rarest and 1 the lowest. By the time you get down to an R-1 you are looking at a population of over 1,500 specimens estimated and once you try to go beyond that any real population estimates are just wild guesses. So there is not much point in trying to make estimates. The URS is an open ended scale starting at 1 for the rarest and increasing with each increasing number The thing is once you get past URS 11 you are once again dealing with populations that are no better than wild guesses. So anything past URS 11 is pretty much pointless. This means for practical rarity you have the old 8 point scale and the new 11 point scale. Not really any great improvement and hardly in indication that the old scale is obsolete. Especially when you consider that the Sheldon R-8 needs three numbers in the URS scale, 1,2, and 3. URS 4 and 5 fairly well matches Sheldon R7, Urs 6 and Sheldon R-6 are fairly equal. Sheldon R-5 is URS 7 and 8 etc. Some might say the URS has "finer" divisions in the population counts, but the Sheldon Scale allows for that as well by using + to indicate a population in the scarcer third of the range and a - for the more common third of the range. In short the URS scale has no real advantage or improvement over the Sheldon Scale.
The Sheldon rarity scale was originally developed and only used for large cents. Later it was somewhat adapted and used for early american and colonials. Later still Breen copied the numbers and R ratings, with 2 exceptions R8 is for 1-3 known whereas Sheldon has R8 at 2 or 3 known, and Unique for 1 known (which some folks refer to as R9). Breen's - Sheldon's - But there are many, many rarity scales. Some of which are also based on Sheldon's scale. But some are quite different and some deal much larger numbers, larger even than URS uses. For example, the Van Allen and Mallis rarity scale - And the Freeman scale for Great Britain Bronze Coinage uses even larger numbers - But unless you get down to where there are less than 20 or so known, yeah, all of the numbers are guesses. But in most cases, educated guesses.
You need to read more Frank. I can't even count the number of posts longer than this one that I have posted. Several within the past couple of weeks. But thanks for the kind words.
The only real problem I have with the URS is when certain folks use it against graded examples. For example, citing a specific URS when only "X" number have been graded by PCGS. As with anything, these tools do not make one an expert anymore than owning a Word Processor makes one an Editor or Typesetter.
