Hi, can anyone help with the following:
1. What is the difference in interpretation of the results being derived from the two following
scenarios?
a) Introduction of a co-variate exclusively as EV1 on the 3rd level, when using a main regressor
linked causally to the co-variate on the 1st level (e.g. individual percept-scores of brightness entered
as a co-variate when using the actual measured brightness of a visual stimulus as the main
regressor).
b) Introduction of an “independent” covariate as EV2 vs. group mean as EV1 on the 3rd level (e.g.
same main regressor as in a), but psychometric data like individual depression-scores entered as
EV2).
2. In 1.: Would it make sense to enter the individual depression-scores exclusively as EV1 on the
third level? If yes, what would the interpretation of the results be?
3. When two stimulus conditions are contrasted on the second level (within subject, e.g. central vs.
peripheral visual field stimulus presentation) and then entered into a 3rd level analysis (between
subjects), what is the interpretation of results derived from introducing a co-variate on the 3rd level?
Thank you very much,
Morten
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