Since carbon is fundamental to life, occurring along with hydrogen in all organic compounds, the detection of such an isotope might form the basis for a method to establish the age of ancient materials. Libby, a Professor of Chemistry at the University of Chicago, predicted that a radioactive isotope of carbon, known as carbon-14, would be found to occur in nature.Measurements can be made with a high degree of precision. Aardsma submitted a sample from a reed mat known to be over 5,000 years old.The measurement, before calibration, came back with an error bar of /- about 60 radiocarbon years. It should be noted that these measurement uncertainties do not increase linearly as one goes back in time.
Thus there are statistical counting uncertainties proportional to the square root of the number of atoms counted.
It is confusing when the maximum date for Carbon 14 is listed as 60,000 years and 80,000 years in the same article (Chapter 4 Dating Methods by Roger Patterson and the reference article summary 4.2 by Riddle.) and as 50,000 years in another (The Answers Book) as well as 95,000 years in the Creation College lecture by Dr. This is why there is the disparity in the quoted limits to radiocarbon dating, as highlighted by this inquirer.
This is due to the fact that the AMS instrument has to be calibrated, and yet the organic materials used for calibration (that are supposed to be so old they shouldn't have any detectable radiocarbon left in them) all contain so much radiocarbon that it means samples of unknown age can't yield dates above this radiocarbon barrier.
The precision of a radiocarbon date tells how narrow the range of dates is.
There are two main factors which determine the precision of a radiocarbon date.