I would like to conduct a regression with 4 continuous variables. One dependent and 3 independent. Between 2 independent variables I would like to test the interaction moderating effect as well.
The difficulty that I don't understand is that my model is based on 36 cases in 4 different time periods. This means 36 airline carriers are studied for 2004, 2005, 2006 and 2007. For the regression this means I have a total of 144 observations (36 x 4) in one data sheet for which I'd like to run a regression?
Although I am reading things like the decision between ordinary least squares, generalized least squares, choosing between fixed or random effects. Can somebody help me and explain which analysis method in SPSS I need to use to run a regression, and if required how I should decide and interpret the fixed and random effects decisions.
Thanks in advance.