A method used to obtain the most accurate dating, especially with radiocarbon dating. The term refers to the adjustment of dates in radiocarbon years by means of the dendrochronological data so that a date in calendar years is achieved. Fluctuations in the amount of carbon 14 in the atmosphere mean that radiocarbon dating is not completely accurate. By obtaining radiocarbon dates for wood of known dendrochronological date, a correction factor can be introduced to calibrate radiocarbon dates. Uncalibrated dates are raw dates in radiocarbon years. Accurate calibration of radiocarbon dates are not possible before 6285 BC.