I am evaluating three independent samples (1-3). For each sample I have calculated a correlation of variables A and B.
I am now interested if there is a linear trend in the development of the correlations from sample 1 to sample 3. I have already detected that the correlations for the three samples are significantly different from one another.
For linear trend analyses I have only found ways, in which you can analyze the development of one variable over different samples, but not of the correlation of two variables over different samples.
Is there a way to calculate this?
UPDATE: I think I need to specify a little more: I have the data of 3 classes (3rd, 5th and 7th). The students have all been tested in the same tests. I am interested in the relation of the two variables AxB and therefore I have calculated the correlation for these two variables (for all three class-levels). For the 3rd grade the correlation is close to zero. For the 5th grade the correlation is somewhat higher but still very small and for the 7th grade the correlation is moderate. I have already detected that the correlations are significantly different from one another. I am now interested if the obvious change in the correlation is following a trend and I am trying to find a way to calculate this.
UPDATE 2: Unfortunately I cannot comment because I still need more reputation-points. Based on your question, what I am interested in is a way to find out, if the change of the relation of variable A and Variable B between groups/class levels (shown in significant different correlations from grade 3 to 7) is due to a linear change of variables A and B in between groups/class levels. I don't have any well-grounded theoretical base to assume which of both variables influences the other.