Dear SPM experts,
I have been reading in the archives topics which relate to my following problem but I ended up a bit confused with no confidence regarding what is best to do and why.
I would be more than happy if you could help me to understand the issue of sphericity and solve my specific problem to ensure a good design for the analysis.
My experiment has two subject groups (25 in group 1 and 21 subjects in group 2). Each subject perform 2 types of task (i.e. 2 conditions).
I am interested in both: in-between subjects effects and within-subjects effects. So for the 2nd level analysis I set the model specification with Full-Factorial Design with 2 factors (f1: task type, f2: subject group). f1 has 2 levels for the two types of task and f2 has also 2 levels for the two group of subjects.
I understand that in this ANOVA design analysis I included both the between-subject analysis (the f2) and the within-subject analysis (the f1).
My questions are the following:
1. What should I choose regarding the independence (yes/no) and the variance (equal/unequal) in my design? And most importantly why?
2. Does my design fit for my question or should I use other type of design such as flexible factorial design? And if so what shall be the parameters then?
3. If there is anything else that I should know or check in my design please let me know.
I thank you very much in advance,
Alec
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