we are currently working on our thesis and the data we have gathered poses a problem for us.
We have an unbalanced panel with observations for corporate givings amount. We would like to measure the relationship between corporate givings and subsequent financial performance. Financial performance is the dependent variable and corporate givings the independent variable. Additionally, there are some control variables included. The panel is unbalanced because we do not have data from each company for each point in time.
We would like to compute a curvilinear relationship between the two variables. I read that with unbalanced panels you have to use Linear Mixed Model but we do not get any output with that.. Also I am not sure if you can get a curvilinear relationship with LMM??
Does someone have an advice how we can proceed? We really really need the help right now!