I have narrowed my options down to Minnesota and Northwestern that offer similar stipends. I just received the NSF fellowship, and Minnesota offered me $7,000 per year to supplement the NSF fellowship. Northwestern has not offered me anything additional. I plan on going to Northwestern regardless of any additional funding. Is it inappropriate to negotiate funding at Northwestern? If it is fine, does anyone have ideas as to how to go about doing this (i.e. talk to graduate adviser, POI, etc.)? Any help is appreciated.