nested and crossed effects in mixed

[Costas Anastas]

Hello together,

I have a question concerning the structure of my data and the way I should feed it in the mixed command:
- I have 100 participants nested in 3 distinctive groups.
- All participants underwent the same experiment which consisted of 4 distinctive "trials".
- During each trial we measured the dependent variable in total 55 small "regions", which are the same among participants and can be grouped in 5 bigger "region groups". Regions is nested in region groups. Region groups is somehow nested in trials, or the other way around (I am not sure), because region groups characteristics are shared among trials.
Summary of the data: I have 55 values for each participant, splited in 4 trials, and 5 region groups. Now I dont care about each region by itself, but more about region groups.
I want to allow for a different random intercept for each participant in general and also for each region/region group respectively.
The independent variables will be the distinctive groups and the trials.
xmixed y i.group i.trial ||regiongroup_ind:||region_ind: is a good start I guess, but how can I add a random intercept for each participant as well?

thanks for your suggestions in advance

[William Lisowski]

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