3. Make a collection of samples in CDendro

From the two previous lessons we know that NMBS01.POS and NMBS05.POS are two samples which match well when their first years (0) lay over each other.

We will now add these two files together as a collection and then make a "mean-value-sample" out of it.

Then we will match yet another of the files from Bergvik towards that "mean-value-sample", and then add it to the collection.

1. Open NMBS05.pos and select it as the reference

2. Open NMBS01.pos and run a correlation analysis to make sure that the files match together.

Note: You may select several sample files at the same time: Hold down the control key and click on those files you want to open. Then click open.

Click on Collections on the menu bar and then click Create new collection. The new collection will automatically be selected as the "target collection", i.e. when samples are added to a collection they are added to this "target" collection.
Now you have an empty basket to collect your samples.

Click on the top of NMBS01.pos to make it the uppermost (not hidden) window.

You can also select it from "Window" in the menu bar as shown in the picture above. If you prefer to work with maximized windows, this is the menu for switching between windows!

Click on the button "Add to target collection"

A new window for setting an offset will pop up - just click OK to accept zero as the offset.

To see what actually happened, click on the top of the collection window, so you can see your sample in that basket!

Now select the other sample NMBS05.pos and then add also that sample to the collection so you get two samples in the collection! Also this one should have zero offset as we know that the samples are of the same age and they fit together at their beginnings.

Close both windows NMBS05 and NMBS01: First select a window by clicking on the top of it, then click the close button at the top right corner.

Note: You cannot make a non-selected window close properly by clicking on its close button. You first have to select the window, then close it.

Now we will calculate a mean value of these two samples.

Click on the button "Create mean value sample"

A new "sample" has been created. It consists of mean values of ring width data and mean values of normalized data created from our two samples from Bergvik.
We could name this a very simple reference curve!

In the diagram you see that "reference curve" as a group of red curves plotted from mean values of the normalized data of the samples included in the reference - and as a group of green curves plotted from the mean values of the ring width data of the samples.

The red and green curves in the middle of the two tripple-curve-groups are the real mean value curves.
The outer (enclosing) curves are based on standard deviation values - not of much interest when mean values are based on only two curves, of much more interest when there are many samples in a collection.

Click on the Workbench tab!

The report shows how many ring width values there are behind the mean value for each year.
There are two years for the first 83 years. Between 84 and 101 there is only one value for each year because there were more ring coordinates in NMBS05.pos than in NMBS01.pos

You should now add a third sample to the collection, and then calculate new mean values.

Click on the button "Select as reference", so you can match the next sample towards this mean-value-sample.

Then open the next sample file NMBS08.pos!

Click the button "Make corr. analysis" and inspect the curve matching! Then click the Workbench tab!

Please observe that this sample matches best at year 3 in the reference (which was created out of the collection).

Click on the button "Add to target collection"!

You are prompted for the offset to use when adding this third sample to the collection.
See there is a 3 in the offset field!

Close the NMBS08.pos window!

Now look at the collection list!

In the Offset column you have the relative years covered by data from the corresponding member file.

If you want to delete a member of this collection, select it by clicking on it and then hit the Delete member button!

You can attach a comment to a member: Select it by right-clicking on it to open an edit window! Here you can also change the offset value. - You can even change the identity of a member!

Save the collection file. Use the name NMBS1_5_8.fil (Click on "Collections" on the menu bar, then "Save collection As"). Then close it.

Close also any other open file.

Note: A collection can be saved either as a collection file (extension .fil) or as a decadal file (extension .rwl or .fh (Heidelberg formatted)).
The collection file (.fil) contains only filenames, comments and offsets - NO ring width data!
When you save a collection in a .rwl decadal file, you get a file with all ring width data written in the same format as files in the ITRDB. (International tree ring data bank in Arizona). Though normally the files published in the ITRDB do not normally contain comments even if that would be formally accepted. You have two commands in the Collection-menu for writing in decadal format: Either put your comments into the .rwl file or put them into a separate .txt file. More on the decadal format in a subsequent lesson.

Note: When you save a "mean-value-sample" created with the button "Create mean value sample" in a collection you save it either as normalized mean value data (.d12 format) with standard deviations and ring widths with standard deviations or as only ring width mean values in one of three possible formats - .wid, .rwl or .fh

There are four different ways to get a "mean-value-curve" with standard deviations on the screen:
1. Open a normalized (.d12) file with a mean value curve created as mentioned above.
2. Open a collection "Open collection (.fil)" with all its members and click on the button "Create mean value sample"
3. Use the command Collections/Create new collection from decadal file (.rwl), click the "Create mean value sample".
4. Use the command Collections/Create reference curve from big decadal file (.rwl or .fh).

Note: In early versions of CDendro ".dec" was used as the file extension for decadal files. When the ".rwl" extension was introduced in CDendro, the old .dec-extension was kept to make it possible to open old files with the .dec extension.

See also the section on Multi-radii collections, i.e. when several radii are taken from the same trunk.