• by Mark Walsh  @markfwal, July 15, 2011

There's no question social networking is expanding onto cell phones. The 250 million -- and counting -- mobile users of Facebook alone attest to that fact. But the proportion of U.S. mobile users who access social networks on their devices isn't quite as clear.

New findings released today by ABI Research indicated nearly three-quarters (73%) use their phones to visit social networking sites daily, sometimes more than once each day. That figure appears to vary widely from comScore's estimate that 28.6% of U.S. mobile users accessed a social networking site or blog for the three months ending in May.

Similarly, second quarter data from Nielsen shows 31% of mobile subscribers said they had used their phones for social networking in the past 30 days. And a Pew study last year found 23% of American cell owners had used their phones to access a social networking site.

So what gives with the ABI estimate?

The market research firm says its finding was based on an online survey of 2,000 U.S. consumers in March, each of whom owned at least one mobile phone, smartphone or media tablet. They were asked a wide range of questions about how they use mobile devices. Other findings showed 80% checked email, 63% weather or news, and 53% stock quotes daily, for instance.

The comScore data comes from a larger sample of 10,000 mobile users, so it may reflect a broader swath of the U.S. mobile population. It may also include a lower proportion of smartphone users than the ABI sample, which could lead to results showing lower levels of mobile content usage. Smartphone users tend to be more active in non-voice mobile activities. For example, comScore says that among only smartphone owners, 60% use their devices for social networking.

If ABI's survey panel skewed more towards smartphone or tablet owners, that could at least partly explain the discrepancy. But ABI analyst Neil Strother suggested it might have more to do with how the firm asked about mobile social networking and other activities in its survey. He said people were first asked, for instance, if they visited a social networking site via mobile at least monthly. If so, they were then asked how often, leading to the 73% figure for people who access social sites daily on mobile devices.

In other words, that high proportion reflects a subset of avid social networkers in mobile rather than mobile users overall. These might be described as the "power users" among mobile owners who go on social networking sites at least once a month. "What it shows is there's a really robust audience from a daily standpoint," said Strother. It also shows how the torrent of research released about mobile data can sometimes be confusing -- if not conflicting.