There are 100 commodities that I am tracking. As I attempt to improve my time series models, VAR and VARMA look like they might provide some improved predictions. All of the literature I find on creating VAR models assume that the modeler has some assumption of which items might correlate. Are there methods/practices in finding the related items systematically without prior knowledge of the commodities?
Toolset (Python): Working with pandas, statsmodels and matplotlib mostly.