After brfox's message, I have been scavenging the net for a database that would allow me to map New Hampshire voting precincts.
I found some data at the USGS, however voting precincts do not match ZIP codes exactly. Also I need latitude/longitude data.
So I parsed the latlong data from Wikipedia, which lists 223 towns. Here it is, feel free to use it or to complete it.
We can do a paired study on adjacent voting precints with different methods, or do a regression analysis with latitude/longitude as extra data.