Table 2

Description of software-modified phone (SMP) users and calls recorded by the SMPs by study centre

Study centreDates of SMP useNo of usersNo of callsNo of operatorsNo of users per operatorNo of days of SMP useNo of calls per dayCall duration (minutes)
Min–maxMeanMin–maxMeanMean
AustraliaNov 03–Jun 0448678214832.817–494.51.71
CanadaJan–Jul 05373395213–2431.812–483.22.08
DenmarkAug–Oct 0346345852–1629.112–412.51.80
FinlandFeb–Mar 0246458141–2927.211–383.92.80
FranceJan–May 0124379633–1125.413–396.71.88
GermanyNov–Dec 01493023222–2725.88–422.71.51
IsraelAug–Dec 02411505814134.29–5010.91.84
ItalyFeb–Mar 03538049316–2027.619–335.41.67
New ZealandNov 03–Mar 0427246612737.322–722.51.61
NorwaySept–Nov 0448394632–2431.314–522.72.42
SwedenApr–May 0346546151–2427.38–424.51.78
UK North 1*Feb–Mar 011760711720.39–321.62.45
UK North 2Apr–Jul 0334252953–1427.010–352.92.17
Total51663151361–4829.38–724.21.96
  • *In the 2001 study in the UK, problems with the phones’ software led to part of the collected data being lost, resulting in few included subjects; the study was therefore repeated in 2003 with a different set of volunteers.