| While analyzing the data in the file CO20050101-LCE-AjC.txt at the French CNRS database I observed a number of quite high TTest correlation values which were not considered as correct datings. |
| A look at the ring width data of some of the files revealed that the lab uses the convention to register very narrow rings with the value "1" as shown above. With these values the surrounding rings will then have values which are between 50-200 times as wide as that narrow ring. (Missing rings - are marked with a ",") |
| The wide span in values will make the Baillie/Pilcher normalized curve (the red curve at the top above) dominated by the narrow ring. |
| When two curves, which both have such a narrow ring, are crosscorrelated with either the Baillie/Pilcher normalization method (as above) or the Hollstein method, these narrow rings will "attract each other", i.e. give a match at the wrong position. |
| Note that the other normalization methods are not fooled by the existence of these extreme narrow rings! |
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Let me show still one more example:
Above are ring width data collected from two Scots pines in 1995.
The data has been somewhat manipulated, by changing one of the narrow rings from 0.140 mm into 0.01140 mm and another narrow ring from 0.240 mm into 0.01240 mm |
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When these two manipulated ring width curves are crossdated towards each other with the
Prop2Yrs (Proportion of two last years growth) method, the correct dating will be "top ranked"
as shown above. Though the Baillie/Pilcher and Hollstein methods will get fooled by those
two very narrow rings!
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