Fraction of Surviving coins

Summary of discussion on Moneta-L eGroup.

From:  Ken Martins KenMartins@a...
Date:  Mon Feb 12, 2001 0:07am
Subject:  (was Raven Index) Percentage of Surviving coins?

<< The "Raven index" is a measure rarely used by name any more. It is,
for an issue that has been the subject of a scholarly die study, the
number of coins known divided by the number of dies known. For most
important Greek silver issues it is above 4 and sometimes above 10. >>

If I understand this correctly, we can surmise, roughly, the
percentage of surviving coins.  For example, Warren stated that the
typical range of "Raven numbers" is 4 to 10.  Let say 7 is the
average.  In the past we have discussed on this list that a die set
may produce somewhere between 500 and 10,000 coins before replacement
or recutting.  Once again, lets assume an average die set produced
2,000 coins.  Therefore, 7 of the 2,000 coins have survived and been
discovered, which is 0.35 percent.

Can the numbers be used this way?  What do you folks think?

From: Robert Kokotailo, Calgary Coin and Antique Gallery Date: 2001 Feb 12, 1:07pm At this time, trying to do any such numbers is pointless. All estimates as to the number of coins per die as simple guess work, as are most of the estimates of the numbers of coins from each die that currently exist. The problem is that most such estimates are based on the specimens that pass through major auctions with images, and are in the few really major collections. They do not take into account the specimens that pass through the market without ever being imaged, which is the bulk of what exists. We basically end up with something like : Original strikings from the die : 10,000 + or - 8,000 Surviving specimens specimens : somewhere between 5 and 50. Average survivial % somewhere between 5 our of 18,000 = .002% and 50 our of 2,000 = 2.5%. Basically it means little. Only for the very rare and expensive coins, which tend to be sold by public auction with images, or only reside in the major collections, can any of the estimates of survivals be expected to be close. But we still have the problem that no one has any real idea how many of each die would have been originally struck.
From: "Chris Freeman" Date: Mon Feb 12, 2001 3:14pm Excellent points. I would add from working with early american copper coinage, original mintage is sometimes entirely irrelevant with regards to survival amounts. There is a die of an early american cent that shattered very early, (known to us since the devices were very sharp, indicating little wear), but is relatively common despite the fact that probably only a thousand or less were minted, but there are other dies that are extremely worn, (indicating heavy use and probably many thousands minted), but are very rare with but a few examples known. The areas where the coins were issued and distributed, both for climate and coinage demand, as well as "luck", whether examples of the coinage happened to be stashed away as savings, are probably much more important to surviving specimens than initial mintage. Given these facts from relatively "modern" coinage, I think we are left to doing census' on desirable ancient coins, always remembering that there is a hoard out there just ready to be discovered!
From: Warren Esty Date: Mon Feb 12, 2001 4:05pm The fraction of coins still surviving is known to scholars as the "survival rate." Fifty years ago, some scholars guessed it was 1 in 5000. Now, many more coins have been found, we have more-sophisticated statistical methods, and far more issues have been die-counted. We know more. But, we still don't know the number of coins struck per die, on average. Some say we can't know and would be best off not to even guess. But, if you are willing to stick to *averages* and not push the data too far, we can give a reasonable crude estimate of the survival rate using the techniques you mentioned, Ken. The data for die-studied Hellenistic Greek coins suggest that important silver Greek coin types worthy of being photographed in major sale catalogs almost always exist in at least 3-10 recorded coins per die. And, these numbers refer to *recorded* coins that are in museums consulted, or coins that have been published in major sale catalogs that the researcher used. That probably leaves out many examples. People (like Ted Buttrey on this list) who participate in ongoing die studies find that, if they keep looking, year-after-year the sample size increases. A thorough study can yield X coins, and ten years later the sample has increased dramatically to 2X or maybe much more! Imagine the difficulties. Write or visit twenty major museums. Pay for photographs. Scour 10,000 sale catalogs (an omit another 10,000 that just might have an example). Photograph those photographs. And realize you have missed almost all the smaller museums in the Greek and Roman world, many coins in private collections in the west, and almost all collections in the regions where the coins were made and lost. Furthermore, many coins have been found since some of those die-studies were done. Those usually don't affect the estimated number of original dies (the estimators are designed to compensate for sample size), but they do increase the number of coins per die. So ten coins per Hellenistic Greek die is probably a minimum average. Now we need a guess at the number of coins struck, on average, from dies. Controversial subject! But, the slim evidence we have suggests it may have been 20,000 to 40,000 coins per die. Many issues, particularly small issues, may have averaged substantially less. But, big issues, like many Roman Republican issues, probably averaged in that range. By the way, very extensive die studies of Republican issues may find about 6 coins per die (Those of you on this list doing die studies may wish to chime in with your numbers). But, very many Republican coins are sold without a permanent record in the form of a printed sale-catalog photograph. Surely there are far more Republican coins extant than have been published. So, take 20,000 coins per die (if you are willing to play with crude numbers and take averages) and divide by, say, 10 coins per die, and you get about 1 in 2000 surviving. For big issues in which the dies were very heavily used (I'm thinking of mid-third century AD radiates), the average number of coins per die may be larger, but the number of coins in huge hoards probably increases the survival rate, too. Of course, there are many caveats. Don't take "one in two thousand" too seriously, but I think it is off by less than a factor of ten. I would not be willing to assume the same numbers apply to AE or gold.