^aIt was unclear how many individual measurements were made at GSM900 and GSM1800 but the authors have assumed that a measurement of each service was taken at each of the 50 base stations surveyed.

^bAdditional data for 2010 provided by Kouakou (private communication).

^cDue to limited detail about the data set the authors were not able to differentiate the GSM900 and GSM1800 measurements but the authors have assumed that a measurement of each service was taken at each of the 106 base stations surveyed.

^dThe South African data were filtered to remove measurements that were within 10 dB of the noise floor for the instrumentation. A detailed discussion of this filtering has been included.

^eThe Zambia data were also filtered to remove data that were clearly noise floor measurements and this resulted in the exclusion of 63 data points predominantly from the GSM1800 measurements.