Methodological Issues

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The main ambition of this website is to estimate the volume of ancient coin production. This is a topic which, once hotly debated [[CiteRef::Buttrey 1993]] [[CiteRef::Buttrey - Cooper 1994]] [[CiteRef::Callataÿ 1995b]] [[CiteRef::Buttrey - Buttrey 1997]], is now generally accepted as worth to be pursued [[CiteRef::Callataÿ 2005b]].  
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The main ambition of this website is to estimate the volume of ancient coin production allowing comparisons not only in recorded or original numbers of dies, but also in numbers of coins and even, for precious metals, in weights of silver. This is a topic which, once hotly debated [[CiteRef::Buttrey 1993]] [[CiteRef::Buttrey - Cooper 1994]] [[CiteRef::Callataÿ 1995b]] [[CiteRef::Buttrey - Buttrey 1997]], is now generally accepted as worth to be pursued [[CiteRef::Callataÿ 2005b]].
  
The common strategy is a two-step process: first, to determine the number of original dies from the number of recorded dies in the sample. The second step is to multiply the original number of dies by what we think was the average production of a die.  
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The common strategy is a two-step process: first, to determine the number of original dies from the number of recorded dies in the sample. The second step is to multiply the original number of dies by what we think was the average production of a die. Another strategy developped by Warren Esty is to estimate the coverage, i.e. the relative part taken in the full production by the 
 
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<div class="card-header bg-light"><h5><span class="fas fa-hammer"></span> [[Die Studies Database|Why an average of 20,000 coins per obverse die?]]</h5></div>
 
<div class="card-header bg-light"><h5><span class="fas fa-hammer"></span> [[Die Studies Database|Why an average of 20,000 coins per obverse die?]]</h5></div>
 
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The average productivity for an obverse die has been here uniformly fixed here to 20,000 coins. It is a stopgap measure that applies primarily to large money denominations such as tetradrachms, as an estimate which could be divided or multiplied by two (from 10,000 to 40,000 coins), but unlikely by three (from 6,666 to 60,000). Although remaining in the right order of magnitude, this average of 20,000 coins per obverse die is likely to be adjusted for smaller silver and bronze issues. For gold
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The average productivity for an obverse die has been uniformly fixed here to 20,000 coins. It is a stopgap measure that applies primarily to large silver denominations such as tetradrachms. It is an estimate which could be divided or multiplied by two (from 10,000 to 40,000 coins), but unlikely by three (from 6,666 to 60,000). Although remaining in the right order of magnitude for smaller silver denominations and other metals, this average of 20,000 coins per obverse die is likely to be adjusted depending of the kind of coinage.

Revision as of 14:17, 15 May 2023

The main ambition of this website is to estimate the volume of ancient coin production allowing comparisons not only in recorded or original numbers of dies, but also in numbers of coins and even, for precious metals, in weights of silver. This is a topic which, once hotly debated 1 2 3 4, is now generally accepted as worth to be pursued 5.

The common strategy is a two-step process: first, to determine the number of original dies from the number of recorded dies in the sample. The second step is to multiply the original number of dies by what we think was the average production of a die. Another strategy developped by Warren Esty is to estimate the coverage, i.e. the relative part taken in the full production by the

The first step is to estimate the original number of obverse dies, because they generally deteriorate slower than the reverse dies (on this issues, see 6). The three essential values are: 1) the number of observed dies in the sample ("o"), 2) the size of the sample (the number of coins: "n"), and 3) the number of singletons, i.e. the number of dies attested by only one coin ("f1"). More than 20 methods based on probability calculation were proposed in the 1970s and 1980s. Several contributions have demonstrated the similarities of results between these formulas, providing the ratio 'number of specimens divided by the number of obverse dies' is high enough 7. Let us say, roughly, that these calculations need some carefulness below a ratio of 3, are potentially dangerous below a ratio of 2 and must be avoided preferably below a ratio of 1.5. A majority of coinages fall well beyond that limit. With at least 600 coinages with a ratio "n/o" above 6 and even 45 above 30 [[1]]. Looking at the recent literature, it looks as though nobody is still frightened by that kind of calculations. In other words, the possibility to estimate the original number of dies has been accepted. It was first and for a long time opted for a binomial (i.e. Gaussian, or symmetric) distribution (Good, Carter), with no infantile mortality (A). This is clearly an unlikely model. In the 1980s, one moved to a Poisson distribution with a negative asymetric curve (B). Around the same time, looking at hundreds of real distributions, a combination of a negative distribution (for the infantile mortality) followed by a binomial distributon (for the surviving specimens) was first proposed 8.

To estimate the average number of coins produced by each (obverse) die is a much more debatable issue. While it is easy to produce a long list of reasons for which this average should have varied depending of the metal, the denomination, the tools, the level of technical skills etc., it turns out that every time one may exercise some control, cheking through coin hoards, results are similar (as for the coinages in the name of Alexander the Great, the cistophoric tetradrachms in Asia Minor or the Roman Republican denarii).The reasons which allow the argument for such a figure are various and have been discussed several times. Much has been said about the accounts of the Amphictionic League, indeed a good starting point if only because it is the only (not exactly) straightforward evidence 9 10. Much has also been said about modern experimentations, even if I personally doubt that they could provide anything else than a minimal number. Much less has been said about the few cases for which we do have more than 1,000 coins struck with the same die, also as minimal figures (the Rhodian imitations in the name of Hermias struck by Perseus from the hoard of Larissa [IGCH 237] or the bronzes of Apamea from the hoard of Aphrodisias [the number of 6,000 has been reported]) or the few cases of extremely well dated instances of intensive production with realistic figures of c. 3,000 coins produced per day if using an average of 20,000 coins per die (Mithridates Eupator in 89 and 75 BCE, the joint reign of Justin and Justinian during 17 weeks [April 4th–August 1st, 527 CE]). And nearly nothing has been said about what could be deduced from survival ratios put in perspective, i.e., the fact that Greek coinages are considerably better documented today than medieval coinages and even modern coinages 11. Recent die studies often show an n/o ratio superior to ten (with 8.84, the Yehud coinage is close to that). Then, if we postulate an average output per die inferior to 10,000, we have to assume a survival ratio superior to 1 out 1,000 which is very high if put in perspective (c. 1 out of 5,000/10,000 for medieval coinages and c. 1 out of c. 2,000/3,000 for eighteenth century coinages).

The average productivity for an obverse die has been uniformly fixed here to 20,000 coins. It is a stopgap measure that applies primarily to large silver denominations such as tetradrachms. It is an estimate which could be divided or multiplied by two (from 10,000 to 40,000 coins), but unlikely by three (from 6,666 to 60,000). Although remaining in the right order of magnitude for smaller silver denominations and other metals, this average of 20,000 coins per obverse die is likely to be adjusted depending of the kind of coinage.

References

  1. ^  Buttrey, Theodore V. (1993), "Calculating ancient coin production : facts and fantasies," Numismatic Chronicle, 153, p. 335-351
  2. ^  Buttrey, Theodore V. - Cooper, Denis (1994), "Calculating ancient coin production II : Why it cannot be done," Numismatic Chronicle, 154, p. 341-352.
  3. ^  Callataÿ, François de (1995), "Calculating ancient coin production : Seeking a balance," Numismatic Chronicle, 155, p. 40-54.
  4. ^  Buttrey, S. E. - Buttrey, Theodore V. (1997), "Calculating ancient coin production, again," American Journal of Numismatics, 2nd ser., 9, p. 113-135.
  5. ^  Callataÿ, François de (2005), “A quantitative survey of Hellenistic coinages: recent achievements”, in Zosia H. Archibald, John K. Davies and Vincent Gabrielsen (eds.), Making, Moving and Managing. The New World of Ancient Economies, 323-31BC, Oxford, Oxbow, p. 73-91.
  6. ^  Callataÿ, François de (1999), “Étude de technique monétaire : le rapport ‘nombre de coins de revers/nombre de coins de droit’ à l'époque hellénistique”, Revue des Archéologues et Historiens de l’Art de Louvain, 32, p. 91-102.
  7. ^  Callataÿ, François de (193), “Estimation du nombre originel de coins : en augmentant l'échantillon...”, Acta Numismatica, 21-23 (Essays in honour of L. Villaronga), p. 31-48.
  8. ^  Callataÿ, François de (1987), “Statistique et Numismatique : les limites d'un apport”, Revue des Archéologues et Historiens d'Art de Louvain, 20 (Mélanges J. Trizna), p. 76-95.
  9. ^  Kinns, Philip (1983), "The Amphictionic Coinage Reconsidered", The Numismatic Chronicle 143, p. 1-22, pl. 1-4.
  10. ^  Marchetti, Patrick (1999), "Autour de la frappe du nouvel amphictionique," Revue belge de Numismatique, 145, p. 199-113.
  11. ^  Callataÿ, François de (2000), "Les taux de survie des émissions monétaires antiques, médiévales et modernes. Essai de mise en perspective et conséquence quant à la productivité des coins dans l’Antiquité," Revue Numismatique, 155, p. 87-109.