Here is my question:

I have a 4 groups of subjects (between factor) repeating the same task for 10 times in different blocks (within factor).

I want to analyse differences between groups.

What i did was to perform a 4 x 10 mixed design ANOVA and look at possible main effect of "group" or interaction "group x block"

However, since I expect a linear increase of performance across block, I would like to transform the variable block from discrete to continuous.

I use StatSoft - Statistica for the analysis. Does anyone know how to do this step by step?

Thank you very much in advance