it allowed assessment of
the repeatability of use of mobile phones reported earlier.
Of the women who reported at baseline that they
had used a mobile phone, 77% of those reporting ever
use (13 437/17 647) and 92% of those reporting daily
use (1702/1852) also reported use for at least 1minute
per week at follow up, an average of 8.8 years later. In
women reporting use at both surveys, duration of use
reported at the later survey was consistent, on average,
with that estimated to have accrued by that time
on the basis of duration reported at baseline, assuming
continued use between surveys. Approximately
half (49%) of those who reported no phone use at
baseline reported using a mobile phone in 2009.