I think a big problem (and you highlight an outcome here) is that focussing on geo political units like county boundaries which have a huge variance in both area and population is always going to be a troublesome background on which to pin statistics.
One idea might be to distort the map so each county has a size proportional to its population - quite tricky around metropolitan areas! There might be a way to aggregate adjacent counties in some way.
Depending on the raw data granularity it might be best to dispense with political boundaries and say plot based on some form of population to area measure that smears things somewhat. That would probably be fair but wont please anyone with an axe to grind (ie everyone).
You should see the statistical contortions carried out here (UK) for similar bollocks. North/South divide? - where is the middle of the UK? Who knows? Does it include Scotland, Northern Ireland and Wales? Where exactly are the Midlands? Is Wiltshire in the South West or the South? Anyway you get the idea.
You end up spending more time explaining outliers and oddities than you do focussing on the real issues (whatever they are) with these kind of maps unless they are very, very carefully and rigorously put together. A fair and rigorous map will probably please no-one 8)
Oh and another thought - if your post (sorry) zip codes are involved in the raw data then as a previous article on HN showed they don't always map very well to the boundaries they purport to cover.
One idea might be to distort the map so each county has a size proportional to its population - quite tricky around metropolitan areas! There might be a way to aggregate adjacent counties in some way.
Depending on the raw data granularity it might be best to dispense with political boundaries and say plot based on some form of population to area measure that smears things somewhat. That would probably be fair but wont please anyone with an axe to grind (ie everyone).
You should see the statistical contortions carried out here (UK) for similar bollocks. North/South divide? - where is the middle of the UK? Who knows? Does it include Scotland, Northern Ireland and Wales? Where exactly are the Midlands? Is Wiltshire in the South West or the South? Anyway you get the idea.
You end up spending more time explaining outliers and oddities than you do focussing on the real issues (whatever they are) with these kind of maps unless they are very, very carefully and rigorously put together. A fair and rigorous map will probably please no-one 8)
Oh and another thought - if your post (sorry) zip codes are involved in the raw data then as a previous article on HN showed they don't always map very well to the boundaries they purport to cover.