Google is confusing. How do I get real USA search results?

I am outside of USA. All this time, I've been using /ncr thinking that I am getting USA search results. It was weird though that I am not getting that much traffic even when I am on the first page of google. So I decided to check using a different method. I tried using a VPN with USA server and my rank is totally different!

I also tried this website
http://wwp.greenwichmeantime.com/time-zone/usa/websites/google.com/google-usa.htm/

My rank is also different for some keywords.

I then use SEO Global tool for Firefox using USA search results. Its different aswell.

Which is which? I am getting extremely confused and I want to know what rank I am in in the USA Google search engine.

Results vary based on your ip, even within the USA though you would get very little differences. Use rank trackers like microsite masters, prorank tracker etc and specify USA results for a good idea on your keyword rankings.

use Google.com and try the results. Even GA data varies by extensions.

Thanks guys! But what about /ncr? Does it actually give USA results?