Their results were 'two to three times less accurate than implied by the range of error they stated.' They thought the variations might have been caused by poor laboratory standards allowing contamination of the samples.
Some scientists believe the problem runs far deeper than this, as the following quote shows: In the light of what is known about the radiocarbon method and the way it is used, it is truly astonishing that many authors will cite agreeable determinations as "proof" for their beliefs...
The radioactive carbon has six protons and eight neutrons in its nucleus, giving it a total atomic mass of 14.
Thirty-one of the labs gave results that the British group called unsatisfactory.As you might guess, radioactive carbon (C) is quite rare.Only one out of every trillion carbon atoms is C14. The C14 created in the upper atmosphere reacts with oxygen to become carbon dioxide.The nitrogen atom, which began with seven protons and seven neutrons, is left with only six protons and eight neutrons.As the number of protons decides the chemical nature of an atom, the atom now behaves like a carbon atom.When they strike ordinary atoms in the upper atmosphere, the cosmic rays smash them apart. Some of these neutrons then collide with nitrogen atoms.This collision is less destructive than the initial collision that produced them.The ions produced are forced into a magnetic field where the different mass of the carbon isotopes causes a different deflection, allowing the quantity of each isotope to be measured.This method is claimed to be more accurate than the older and slower method of counting the number of radioactive decay emissions from a quite large sample.However, because it has too many neutrons for the number of protons it contains, it is not a stable atom.Every 5,730 years, approximately half of this radioactive carbon spontaneously converts itself back into nitrogen by emitting an electron from a neutron.