A regular theme that I have to deal with is multiple mobile device or SIM ownership. Statistics are very fuzzy on this - you get the usual estimates of 120%+ penetration, but very little analysis of what that means in reality.
Vodafone occasionally tries to estimate the level of multiple SIM ownership in its markets, and I commented on a survey on the UK market recently which seemed to suggest 1.6 SIMs per person, but definitions seemed questionable, eg with penetration of phones among children.
I thought I'd try and come up with some slightly harder numbers.
The UK has 70m SIM registrations at the moment, and 60.8m people, with a demographic breakdown given here. Last year, Carphone Warehouse did some analysis of mobile penetration among children up to age 12, while Ofcom has some great research (figs 15 & 16) on the proportion of adults who personally use mobile phones.
This yields the data that 86% of people >15 years old are active users. This is heavily skewed by older people - only 52% of over-75s use mobile in the UK. Among children, from the CPW study there is near-zero penetration among 8-year olds & below, 20% @ 9, 50% @ 10, 70% at 11 and 90% at 12. Given the other data it seems reasonable for me to assume that about 93% of 13 & 14 year-olds are users. The youth data is a year old, so might have shifted slightly, but it's a good starting point.
Multiplying this all through by the population stats gives me:
Total UK Mobile Users = 46.4m individuals - ie 76% of the total population.
Total UK non-users = 14.5m (mostly young kids & seniors)
I'd estimate 1-1.5m SIMs are used in non-personal M2M applications (EPOS terminals, vending machines, wireless routers etc, but excluding laptops & PDAs which are personal devices).
So.... 69m personal mobile subscriptions among 46m active mobile users =
1.46 Mobile Subs / Active User in the UK.
This excludes UK citizens who have international SIMs as well (although probably some of the UK SIMs go abroad too).
What remains slightly unclear is the mix of people with 1SIM+Multiple Devices vs. Multiple SIMs+single device. ie the ratio between active subs/person and active phones/person. Travellers often put local SIMs into a single phone when abroad, but users who like phones for fashion reasons may swap a single SIM among multiple devices.
What this all categorically tells me is that the "one mobile device" philosophy is completely inapplicable in the UK. My rough estimates are
Zero Subs = 24% of all UK individuals
1 sub = 49%
2 subs = 17%
3 subs = 7%
4+ subs = 3%
Bottom line = a majority (51%) of the total UK population either has zero mobile subscriptions, or multiple. People with just a single active SIM are actually in the minority (49%).