השוואת שיטות

	Contextual Seriation	Radiocarbon Calibration
תחום	ארכאולוגיה	ארכאולוגיה
משפחה	Process / pipeline	Process / pipeline
שנת המקור	1899	2020
הוגה השיטה	W. M. F. Petrie (sequence dating); formalized as occurrence seriation by mid-20th-century quantitative archaeologists	Hans Suess (first curves); IntCal Working Group (P. J. Reimer et al.)
סוג	Relative-chronology ordering of units by presence-absence of types	Probabilistic conversion of radiocarbon ages to calendar ages
מקור מכונן	Lyman, R. L., & O'Brien, M. J. (2006). Measuring Time with Artifacts: A History of Methods in American Archaeology. University of Nebraska Press. ISBN: 9780803280526	Reimer, P. J., et al. (2020). The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0-55 cal kBP). Radiocarbon, 62(4), 725-757.
כינויים	Occurrence Seriation, Sequence Dating, Incidence Seriation	14C Calibration, IntCal Calibration, Calendar Calibration of Radiocarbon Dates
קשורות	3	3
תקציר	Contextual seriation, also called occurrence or sequence seriation, is a relative-dating method that orders discrete archaeological units — typically graves or closed deposits — using only the presence or absence of artifact types within them. Its logic is the lifespan assumption: each type is introduced, used continuously for some span, and then disappears, so the contexts in which a type occurs should form an unbroken stretch of the sequence. By permuting the rows and columns of a presence-absence matrix until every type's occurrences cluster into a single contiguous block, the analyst recovers a one-dimensional ordering interpreted as time. The technique originates with W. M. F. Petrie's sequence dating of Egyptian predynastic graves and remains a standard tool for chronology where only incidence data, not abundances, are available.	Radiocarbon calibration converts a laboratory radiocarbon measurement into a probability distribution over actual calendar years. It is necessary because the assumptions behind a raw radiocarbon age are not exactly true: the concentration of carbon-14 in the atmosphere has varied over time, so a measured radiocarbon age does not equal a calendar age. Calibration corrects for this by comparing the measurement against an internationally agreed curve — currently IntCal20 — that records the relationship between radiocarbon age and calendar age, reconstructed from precisely dated tree rings, corals, speleothems, and other archives. Because the curve wiggles, calibration typically yields an irregular, sometimes multi-peaked range of calendar years rather than a single date, and that range is the proper expression of a radiocarbon result.