What we’re seeing in Alabama goes beyond the usual warnings about minding the margin of error, however. There’s a massive spread in results
from poll to poll — with surveys on Monday morning showing everything from a 9-point lead for Moore to a 10-point advantage for Democrat Doug Jones — and they reflect two highly different approaches to polling.
Most polls of the state have been made using automated scripts (these are sometimes also called IVR or “robopolls”). These polls have generally shown Moore ahead and closing strongly toward the end of the campaign, such as the
Emerson College poll on Monday that showed Moore leading by 9 points. Recent automated polls from
Trafalgar Group,
JMC Analytics and Polling,
Gravis Marketing and
Strategy Research have also shown Moore with the lead.
But when traditional, live-caller polls have weighed in — although these polls have been few and far between — they’ve shown a much different result. A
Monmouth University survey released on Monday showed a tied race. Fox News’s
final poll of the race, also released on Monday, showed
Jones ahead by 10 percentage points. An
earlier Fox News survey also had Jones comfortably ahead, while a
Washington Post poll from late November had Jones up 3 points at a time when most other polls showed the race swinging back to Moore. And
a poll conducted for the National Republican Senatorial Committee in mid-November — possibly released to the public in an effort to get Moore to withdraw from the race — also showed Jones well ahead.
There weren’t many details released to the public about the methodology of the NRSC poll, but the party committees generally have a lot of money and prefer to conduct traditional, live-caller polling when possible.
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What accounts for the differences between live-caller and automated polls? There are several factors, all of which are potentially relevant to the race in Alabama:
- Automated polls are prohibited by law from calling voters on cellphones.
- Automated polls get lower response rates and therefore may have less representative samples.
- Automated polls may have fewer problems with “shy” voters who are reluctant to disclose their true voting intentions.
- Automated pollsters (in part to compensate for issues No. 1 and 2 above) generally make more assumptions when modeling turnout, whereas traditional pollsters prefer to let the voters “speak for themselves” and take the results they obtain more at face value.
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