Habe mir die Beiträge auf der englischen Wikipedia durchgelesen, muss aber einräumen, dass ich da nur Bahnhof verstehe:
In econometrics and statistics, a fixed effects model is a statistical model that represents the observed quantities in terms of explanatory variables that are treated as if the quantities were non-random. This is in contrast to random effects models and mixed models in which either all or some of the explanatory variables are treated as if they arise from random causes.
