| There are a few standard settings in CDendro that you might change: |
|
Old times to the right (default) or old times to the left (as with most diagrams in a book)? |
|
Curves can be plotted with old times to the right (default) or to the left.
The default setting is a relict from early versions of CDendro when this was the only way to plot.
Today you can have the curves plotted the way you want. Change the setting through the menu command Settings/Plotting window settings.
Then uncheck the box "Plot curves with old times towards right" to get the curves look as conventionally in books and journals.
Note: Old examples within the help texts have old times plotted towards right! |
|
CDendro has a mechanism to crop a sample, i.e. to cut out a section of a ring width curve and show it within a new "sample window".
Note that in CDendro the ring width index is always counted from the late end of the curve! |
|
The cropped sample in its new window is given the same name as the original but with a default extension of "_BLOCKOF" as shown above.
If you then want to save your cropped sample as e.g. a ring width file, the proposed file name will also be like "6680NY_BLOCKOF.wid" |
|
Although "BLOCKOF" is very clear, you might find it a bit clumsy. Personally I have changed that extension from "_BLOCKOF" to just "_C" (C for cropped).
You can change this through the menu command Settings/More settings/Extension to use in file names for cropped blocks. We recommend using the more cryptical but shorter string "_C" instead of "_BLOCKOF"! |
|
Tree ring width data should best be processed by a high pass frequency filter before any correlation analysis is done on the data.
In CDendro this process is named "normalization", see the section on "Dendrochronology, curve matching and mathematics".
There are a number of normalization methods available. The default method is "Proportion of last two years growth, P2Yrs". On the "Workbench" you can see the results of a correlation analysis done, e.g. --Rel Over *P2Yrs------ (year) -year lap CorrC TTest 10 236 0.69 14.7 (1985) (as dated) 344 69 0.38 3.4 (1651) 25 236 0.19 3.0 (1970) 141 236 0.16 2.4 (1854) ....Normally it does not matter much which method you use, though tests have shown that the P2Yrs method is slightly better than the others. Anyhow there are cases when any of the methods can be fooled to signal a match though it is false. But it is very rare that all methods are fooled at the same time! Therefore we recommend you to enable CDendro to calculate and display correlation values for more than one normalization method! With the settings shown in the picture above, the table above would become: --Rel Over *P2Yrs------ BaPi------- C84F------- BesIE------ Skel- GLK-- (year) -year lap CorrC TTest CorrC TTest CorrC TTest CorrC TTest Chi2 GLK 10 236 0.69 14.7 0.67 13.9 0.65 13.2 0.62 11.9 65.9 0.72 (1985) (as dated) 344 69 0.38 3.4 0.38 3.4 0.33 2.8 0.32 2.7 1.6 0.68 (1651) 25 236 0.19 3.0 0.22 3.5 0.20 3.1 0.19 3.0 8.6 0.58 (1970) 141 236 0.16 2.4 0.07 1.1 0.07 1.1 0.06 1.0 0.3 0.54 (1854) .... |
|
So, to avoid problems, you should setup your Windows system to show your file name extensions! This can be done either for your whole system or for individual directories where you store tree ring data. Warning: When you download a tree ring data file from e.g. the ITRDB database, you might be presented with an option to save
the file as "Save as type: Text document" with the name swed302.rwl
To get the file saved with the proper extension ".rwl", you should change the type from Text Document into "Save as type: All Files" before you click on the Save button! |
March 9 2011, Lars-Åke Larsson, www.cybis.se