Abstract: A method is disclosed for determining a location of a mobile electronic device. The mobile electronic device receives an RF signal providing RF fingerprint data and receives a third party location estimate from a third party service. Location data is collected by a dead reckoning system and corresponds to RF fingerprint data and third party estimates collected for a plurality of locations. A correlation between the RF fingerprint data, the third party location estimates, and location data is determined providing a transform for transforming the third party location estimates into a more accurate location estimate of the mobile electronic device.