I currently have a dataset regarding the auctions of spectrum in different countries over the years. The major problem is that there are many cross-sectional variables.
To be specific, there are different countries, different years and also various bands in which the auctions have taken place. Therefore, in a year, there could be more than one auction price under a specific band (like 1800 MHz) even after treating the countries as separate panels.
I cannot treat it as panel data in Stata because it is says that the time-series variable has more than one year in the entries. Is there any reference papers or books which can help me deal with such complex datasets to perform some regressions or calculate average prices etc.?