The interviewer can activate both the GPS and Wi-Fi and mobile network options in device settings, and let the system decide
which one will capture the location best given the current conditions. It is very convenient, though activating both options consumes battery life very quickly.
How accurately the GPS is
able to capture a location depends on various factors: number of satellites in view, mountains and ionospheric disturbances, signal interference caused by buildings and number of channels on the receiver. Specifications for most GPS receivers indicate their accuracy will be within 5-15 meters, 95% of the time
. This assumes the receiver has a clear view of the sky and has finished acquiring more than three satellites. If the conditions are not ideal
then the accuracy declines rapidly.
Nfield CAPI automatically attempts to capture the current location
of an interviewer when the survey is started. This process happens discreetly in the background and without interviewer intervention. If the required accuracy is not achieved, the interviewer will need to confirm the best available location match manually after completing the interview. The location is saved in paradata
and only persons with assigned rights are permitted to download this to view the locations of the interviews.