Dear SPM & GLM Flex experts,
I’m using GLM flex to model a complex study design. Briefly, we applied a pharmacological treatment vs. placebo to healthy volunteers before they underwent an emotional face task with different emotional categories. Moreover, we are interested in the specific interaction effects of the participants gender & the gender of the facial stimuli. This gives us a complex design with the following factors:
Between subject factors
1.) Treatment (2 levels (treatment (TR) vs. placebo (PL))
2.) Participants gender (2 levels (male (P_M) vs. female (P_F))
Within subject factors:
1.) Emotional condition (5 levels (Hap, Ang, Fea, Sad, Dis))
2.) Stimulus Gender (2 levels (male faces (S_M) vs. female faces (S_F))
Some questions regarding the model creation in GLM Flex:
Question 1:
Regarding the between subject factors: how is the order of the factor groups defined? That means, given we have
IN.Between = [1 2 2]; % like in the online example 1 is for a 1 sample t-test across all the data
IN.BetweenLabs = {{'All'} {'TR', 'PLC'} {'P_M', 'P_F'};
In which order have the number of subjects per groups of the 4 groups (TR_P_M, TR_P_F, PLC_P_M, PLC_P_F) have to be defined using IN.N_subs = [];
Question 2:
Regarding the variances and dependence of the between & within subject factors, is it valid to assume:
1. For the Between-subject factor ‘treatment’ : independence – yes; variance equal
2. For the between-subject factor ‘gender’: independence – yes; variance unequal
3. Within-subject factors ‘Emotional condition’ & ‘stimulus gender’: independence – no; variance equal
Thanks in advance & best regards
Ben
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