Dating medieval English charters
By Gelila Tilahun, Andrey Feuerverger and Michael Gervers
Annals of Applied Statistics, Vol. 6, No. 4 (2012)
Abstract: Deeds, or charters, dealing with property rights, provide a continuous documentation which can be used by historians to study the evolution of social, economic and political changes. This study is concerned with charters (written in Latin) dating from the tenth through early fourteenth centuries in England. Of these, at least one million were left undated, largely due to administrative changes introduced by William the Conqueror in 1066. Correctly dating such charters is of vital importance in the study of English medieval history. This paper is concerned with computer-automated statistical methods for dating such document collections, with the goal of reducing the considerable efforts required to date them manually and of improving the accuracy of assigned dates. Proposed methods are based on such data as the variation over time of word and phrase usage, and on measures of distance between documents. The extensive (and dated) Documents of Early England Data Set (DEEDS) maintained at the University of Toronto was used for this purpose.
Introduction: Our object in this paper is to contribute toward the development of statistical procedures for computerized calendaring (i.e., dating) of text-based documents arising, for example, in collections of historical or other materials. The particular data set which motivated this study is the Documents of Early England Data Set (DEEDS) maintained at the Centre for Medieval Studies of the University of Toronto. This data set consists of charters, that is, documents evidencing the transfer and/or possession of land and/or movable property, and the rights which govern them. The documents in question date from the tenth through early fourteenth centuries and are written in Latin, the administrative language of their time. They were mostly obtained from cartularies and charter collections produced in England and Wales, with a few from Scotland.
A peculiarity of that era is that most of the charters that were issued do not bear a date or other chronological marker. This is particularly so from the time of the Conquest in 1066, until about 1307, when fewer than 10% of the more than one million surviving charters bore dates. (A more complete background to these circumstances is provided in Section 2.) Charters dating from the twelfth and thirteenth centuries, however, are a vital source for the study of English social, economic and political history, and signiﬁcant historical information can be derived when such charters can be dated or sequenced accurately. (For some examples, see Section 2.) The charters comprising the DEEDS data set are derived from among those charters which can in fact be accurately dated, and, speciﬁcally, to within a year of their actual issue. A key aim of the DEEDS project was to produce a reliable data base from which methods for dating the undated charters could be devised.