Will the cell phone voting bloc wind up becoming the November surprise? Zogby has just released a path-breaking presidential poll conducted exclusively on mobile phones. And the winner is John Kerry by a landslide margin of 55 to 40 percent... If the Zogby poll, which was conducted in partnership with Rock the Vote, is a reliable indicator, Tuesday night might not be such a drawn-out, nail-biter after all."What annoys me about this discussion is that it is conducted with such little respect for the math involved, which is all the more annoying because it is very simple math. Three numbers are required:
a. The estimated % of persons-who-will-show-up-to-vote who use only cel phones and so cannot be reached by pollsters.
b. The estimated gap between Kerry and Bush among those who-will-show-up-to-vote and use only cel phones.
c. The estimates gap between Kerry and Bush among those who-will-show-up-to-vote and are not exclusive cel phone users.
The adjusted Kerry-Bush gap is just: (1-a)c+ab
The larger a and (b-c) are, the more of a difference cel phones will make, but the difference is determined by the product of the two and products of proportions get small quickly. I personally can't see the cel phone bias in polls giving Kerry even anything like a full percentage point in the polls. To which one can say, of course, that one percentage point is a big deal in an election this close. To which one can reply, of course, that the cel phone problem--in terms of the potential size of the bias--is almost certainly smaller than the general bias from refusals/other-nonresponders in telephone surveys; the only issue is that it is not so clear which direction that bias is. Bottom line is that it wouldn't surprise me at all if the final result is 2-3 percentage points (or--who knows?--maybe more) different from what the consensus-of-polls predicts on the day of election; the only problem is that it's anybody's guess what direction that discrepancy will be.