Droughts and other variations in the climate make the tree grow slower or faster than normal, which shows up in the widths of the tree rings.
These tree ring variations will appear in all trees growing in a certain region, so scientists can match up the growth rings of living and dead trees.
Geologists often need to know the age of material that they find.
They use absolute dating methods, sometimes called numerical dating, to give rocks an actual date, or date range, in number of years.
Far from being data, these dates are actually interpretations of the data.
As discussed before, the assumptions influence the interpretation of the data.
Recent research by a team of creation scientists known as the RATE (arth) group has demonstrated the unreliability of radiometric dating techniques.