Cooking With Gallup, Per RedState: Generic Congressional Poll Changes Sample Base, Improves Dems' Standing

UPDATE, 11:30 P.M.: Gallup has changed the language describing the July 12-18 poll and says it really sampled "registered voters" instead of "adults," and has included an Editor's note saying that the original description of having used "adults" was wrong.

(Original Post)

There are lots of "creative" ways to generate an artificial sense of momentum for a foundering political party.

Based on information provided at its own report, it appears that the Gallup polling organization may have come up with a new one. Gallup didn't merely play with percentage of Democrats, Republicans, and Independents between poll dates. In the case of a generic Congressional poll done on July 12-18, the organization switched to a significantly different sampling base. Whereas previous efforts on the topic sample registered voters, the July 12-18 poll sampled all adults.

RedState's Neil Stevens notes that in the transition, what was a one-point generic ballot lead for Democrats a week earlier using registered voters zoomed to six points in the July 12-18 tabulation of "all adults."

Stevens posted on this yesterday (HT HyScience), and benchmarked the latest poll to one done from May 24-30 (bolds are mine):

Remember on June 2 when Republicans took a big lead in the Gallup generic ballot? I used it to project conservatively a 45 seat Republican gain in the House. This was a poll of registered voters, according to Gallup’s Survey Methods notes:

Results are based on telephone interviews conducted May 24-30, 2010, with a random sample of 1,594 registered voters, aged 18 and older, living in all 50 U.S. states and the District of Columbia, selected using a random-digit-dial sampling technique.

But now on July 19 that Democrats are showing a big lead, despite the fact that Gallup’s pretty graph now is titled Candidate Preferences in 2010 Congressional Elections, Among Registered Voters, the sampling is different:

Results are based on telephone interviews conducted as part of Gallup Daily tracking July 12-18, 2010, with a random sample of 1,535 adults, aged 18 and older, living in all 50 U.S. states and the District of Columbia, selected using random-digit-dial sampling.

Catch the difference? The Republicans lead with a sample of Registered Voters, but the Democrats lead with a sample of Adults. Someone who trusted Gallup’s pretty, but lying, picture would never have noticed.

It is terribly dishonest for Gallup to string together two different polls as one series, as Gallup does not only in their graphs, but in their write-ups as well.

Assuming all is as Stevens details, poll cooking doesn't get much more blatant than this.

I suppose it's conceivable that Gallup's disclosure is in error, but in the current political and economic environment, it's more than a little hard to take that Democrats have achieved significant generic Congressional ballot gains in the past week. Gallup's post implies that the improvement occurred because "the U.S. Senate passed a major financial reform bill touted as reining in Wall Street." Paraphrasing tennis great John McEnroe in one of his less than perfect moments: They cannot be serious.

It will be interesting, and telling, to see if Gallup sticks with the much less predictive "all adults" metric in future reports on the topic, switches back to registered voters, and/or quietly flushes its latest effort down the memory hole at some future point.

Cross-posted at BizzyBlog.com.