My name is Fernando, I'm a biologist and I also have many statistics questions. Hope you can help me.
First of all:
I'm working with tree radial growth and I have measuraments over 10 months (from september 2010 to june 2011).
This is an average from 10 trees:
I also have metereological data from september to june (ie. precipitation (mm)).
If I make a chart with this data, I can visualize a positive correlation during the first 6 months (growing season), but the last 4 I get a negative correlation. However, this negative correlation is due to the biology of the trees, see:
From march to june there are less precipitation and temperature is also low, so trees do not grow (grow just a lit bit). It is and expecpected behavior.
How can I express this through statistics and prove its significance?