Observers seeking some independent data on the race would not find much in the way of reliable polling. The Democratic automated polling firm Public Policy Polling found Carmona ahead by 2 points earlier this month
, but PPP doesn't call cell phones, meaning roughly 2-in-5 eligible voters have no chance of being contacted by their computers.
PPP does weight their results by age, race and gender to account for these shortcomings, in addition to other sampling quirks. According to national trends, we can expect that not calling cell phones would require younger voters, minorities and males (who are less likely to own landline phones) to be weighted up, while older voters, whites and females (more likely to live in households with landlines) would be weighted down.
"Weighting usually takes care of most of the problems associated with not calling cell phones," said PPP director Tom Jensen.
But as the percentage of cell-only Americans continues to rise, that puts additional strain on these weights and could bias results. Jensen concedes that his firm "may get burned this election cycle" because of this noncoverage bias, though he expressed confidence in their methodology.
The November election will go a long way toward determining the importance of calling cell phones for political surveys. But what is clear now is that the effects are likely to vary across the states. Friday's new report shows that, while some heavily-polled states have high cell-only populations, others have been more likely to retain landlines.
Here's a look at the latest estimates from many of the battleground states at the presidential, Senate and gubernatorial levels this year:
-- Arizona: 38.2 percent (up from 33.2 percent in 2010).
-- Colorado: 38.7 percent (33.2 percent)
-- Connecticut: 18.7 percent (15.3 percent)
-- Florida: 34.4 percent (30 percent)
-- Hawaii: 26 percent (23.1 percent)
-- Indiana: 32.8 percent (28.3 percent)
-- Maine: 31.6 percent (25.7 percent)
-- Massachusetts: 21.3 percent (17.3 percent)
-- Michigan: 35.8 percent (30.8 percent)
-- Missouri: 32.5 percent (25.8 percent)
-- Nevada: 34.7 percent (27.9 percent)
-- New Hampshire: 23.6 percent (17.3 percent)
-- New Mexico: 36 percent (29.9 percent)
-- North Carolina: 32.8 percent (27.1 percent)
-- North Dakota: 41.6 percent (38.1 percent)
-- Ohio: 33.4 percent (28 percent)
-- Virginia: 26.6 percent (22.6 percent)
-- Washington: 33.8 percent (30.2 percent)
-- Wisconsin: 33.8 percent (29 percent)
Not all states are created equal. North Dakota law prohibits robopolls entirely, but some live-caller pollsters in that state's closely watched Senate race might also opt to exclude cell phones to keep costs down. Doing so -- and ignoring the nearly 42 percent of voting-age adults who live in cell-phone-only households -- would make their polls subject to greater noncoverage bias than a poll in Connecticut, where fewer than 19 percent are cell-only.
Furthermore, the rates of the changes within each state show that methods that are found to produce accurate surveys in 2012 may not repeat that accuracy in 2014 or 2016. If a pollster who ignores or calls too few cell phones is accurate in this election, the rapid changes might catch up with them in the next election.
As Americans become even less dependent on landline phones, automated and live-caller landline-only polls are likely to become even more anachronistic. According to Friday's report, that has already happened in many key states this election cycle. Polls in these states that undersample cell phones -- or ignore them entirely -- should be viewed with increased skepticism.