This uncertainty can be expressed as a plot of the probability of obtaining a certain value, and the probabilities are distributed about some central, or mean, value.
Archaeologists, paleontologists, and other researchers have long been interested in dating objects and artifacts in an effort to understand their history and use.
Before Pearson, scientists realized that their measurements incorporated variability, but they assumed that this variability was simply due to error.
For example, measurement of the orbits of planets around the sun taken by different scientists at different times varied, and this variability was thought to be due to errors caused by inadequate instrumentation.
Libby became interested in using the radioactive isotope C) in a sample can be quantified by counting the number of decays that the material undergoes in a specific amount of time, usually reported in counts per minute (cpm).
When Libby began his radiocarbon work in the 1940s, the technology available was still quite new.
Scientific measurements also incorporate variability, and scientists report this as uncertainty in an effort to share with others the level of error that they found acceptable in their measurements.
Even the most careful and rigorous scientific investigation (or any type of investigation for that matter) could not yield an exact measurement.Rather, repeating an investigation would yield a scatter of measurements that are distributed around some central value.This scatter would be caused not only by error, but also by natural variability.Because the method was new, Arnold and Libby were careful to replicate their measurements to provide a detailed estimate of different types of error, and they compared the results of their method with samples of a known age as a control (Table 1).Table 1: Age determinations on samples of known age from Arnold & Libby (1949).