Saturday, September 20, 2008

Follow-up: Stalking elusive cell phone-using voter

A couple of months ago, I ran a post on the interesting methodological question of whether cell phone users with no land-line numbers are an undersampled group in most telephone polling, one that might differ in significant ways from regular phone users (well, I thought it was interesting; if you don't, start your own blog).

Here's an update on that from (for the truly impatient reader, the key words are "margin for error" and "probably larger than any likely effect"):

Over the last two weeks, some of these pollsters have provided updates on the impact of their cell phone samples (or lack thereof):

  • ABC News polling director Gary Langer today describes their cell phone interviewing test in a new blog post today and describes the impact on the overall results as "negligible....The precise changes were 0 for Obama and -1 for McCain among registered voters, +0.7 for Obama and -0.8 for McCain among likely voters." These differences fell well within the survey's margin of error.

  • NBC's First Read included this line in their recap of the latest NBC/WSJ poll: "[T]he poll included some cellphone surveys (we found no significant difference in cell phone respondents as we have from landline respondents." More details on the cell phone sample at the end of the filled-in questionnaire provided by the Wall Street Journal.

  • Keep in mind that these are relatively small scale tests, in which the margins of error for both the base land-line sample and the supplemental cell-phone test samples are probably larger than any likely effect. Gallup and the Pew Research Center have released similar tests based on larger samples that suggest a small benefit (perhaps 2 to 3 points on the margin) benefiting Barack Obama from the inclusion of cell phone only interviewing.

So, while the jury's still out, the suggested conclusion here is a small disappointment for Obama supporters, text-messaging away out there even as we speak, and a small bit of comfort for McCain supporters, hoping that their candidate will one day learn how to fetch his own email: If cell phone users are leaning more heavily toward Obama, as some traditional wisdom predicts, the polls are probably already reflecting that. There appears to be little likelihood of a surprise bump in voting totals from an under-measured legion of iPhone users.

We'll see.

(Props to DemFromCT at DKos.)

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