text: Radiocarbon dating After years of discussion, the Holy See permitted radiocarbon dating on portions of a swatch taken from a corner of the shroud. Independent tests in 1988 at the University of Oxford, the University of Arizona, and the Swiss Federal Institute of Technology concluded with 95% confidence that the shroud material dated to 1260–1390 AD. This 13th- to 14th-century dating is much too recent for the shroud to have been associated with Jesus. The dating does on the other hand match the first appearance of the shroud in church history. This dating is also slightly more recent than that estimated by art historian W. S. A. Dale, who postulated on artistic grounds that the shroud is an 11th-century icon made for use in worship services.
  Some proponents for the authenticity of the shroud have attempted to discount the radiocarbon dating result by claiming that the sample may represent a medieval "invisible" repair fragment rather than the image-bearing cloth. However, all of the hypotheses used to challenge the radiocarbon dating have been scientifically refuted, including the medieval repair hypothesis, the bio-contamination hypothesis and the carbon monoxide hypothesis.
  In recent years, the radiocarbon dating data have been repeatedly statistically analysed, in attempts to draw some conclusions about the reliability of the C14 dating from studying the data rather than studying the shroud itself. The studies have all concluded that the data lack homogeneity, which might be due to unidentified abnormalities in the fabric tested, or to differences in the pre-testing cleaning processes used by the different laboratories. The most recent analysis (2020) concluded that the stated date range needs to be adjusted by up to 88 years in order to properly meet the requirement of "95% confidence".
  Material historical analysis