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**Statistical
methods of investigation**

Today the determination of synchronicities is made aided by software. In contrast to the graphical comparison aided only by a light table from the very beginnings of dendrochronology, the utilization of modern computers and software results in an enormous saving of time. The mathematical, statistical methods for the determination of synchronicities will be briefly described below:

**Correlation
coefficient**

The correlation coefficient (r) tells us about
the deviance from the average curve between the annual ring widths
on the one hand and the reference material of the average curve on
the other hand. Therefore the figure 1 means an absolute alignment
(effectively impossible), 0 means an indifferent position and -1
means an absolute inversion. Thus the figure 0.5 describes a
position rather synchronous than the figure 0.4. But only in
context with the amount of annual rings and the determination of
the so called T-ratio a generally intelligible and evaluative
assertion may be made which is able to specify the statistical
probability expressed as a percentage for instance. A percentage
less than 99% should be rejected as too uncertain. 99.99% in
contrast, would indicate a high degree of probability that the
synchronicity which has been found actually is synchronous to the
calendar. A 100% degree of probability is methodically impossible.
For more information, please see Wikipedia.

**Alignment**

The so called degree of synchronicity (GL =Gleichläufigkeitswert) was the first method to be incorporated into the arsenal of dendrochronology. It describes the linear similarity between the average curve and the sample. The x/n figure and the degree of synchronicity are only distinguished through the mathematical way of notation. The qualitative appraisal of these figures may be compared to those of the correlation coefficient.

**Dating index**

The dating index (D) - first introduced by D. Eckstein – is a combination of the x/n figure and the correlation coefficient. Both methods are weighted in a certain ratio. The figure ≥ 100 does mean a good degree of certainty in a determined synchronicity.

‗

Showing a correlation coefficient of r = 0.744, a corresponding t-ratio of 17.2 and a dating index of 462.296, this comparison shows an extraordinary high degree of certainty (≥ 99.995%), although it may not be optically comprehensible at first glance.

**FR, Normandy:** A workshop for
carpenters at the Château de Gaillon, 25.05. -
02.06.2013

and some more Dendrodates for the
Normandy.

**NL, Schoonebeek - southern Drenthe
area:**

A systematical acquisition of the historical
building stock

**DE, Eastern Frisia - Romanesque
churches:**

Serial investigation of wooden
roofs

**NL, 's-Hertogenbosch:**

Is it possible to localize

historical town fires using
Dendrochronology?

**FR, Normandy:**

Renaissance of Granges after the Hundred Years'
War

**NL, Terborg:**

Archaeologists discovered a

big medieval settlement area

**RO, Central Romania:**

Enigmatic medieval carpentry