As a first step of the analysis, the width of each individual tree ring is measured with a 1/100 mm accuracy using high resolution images of the top plate under investigation. No wood removal is required - the procedure is absolutely non-invasive.
The resulting measurement series is then checked for matching growth patterns against a dated reference sequence using both graphical and statistical methods.
If the synchronisation is successful, the graphs of both series will "snap into place" – like a key into its lock, so to speak - enabling the attribution of a date to the exact year.
In practice an undated sample is never checked against a single reference sequence, but against a database of measurements including thousands of dated tree ring series. Only results that are supported by multiple references are accepted as valid.
In some cases the comparison with available reference data does not yield any match and, as a result, no date can be established. By using a dedicated database for resonance wood, the current success rate is about 80%.