Wednesday, May 20, 2009
When Gallup released a poll last week showing a majority of Americans considered themselves pro-life (51%-42%), opponents of abortion used the data to show that President Barack Obama’s liberal policies had galvanized Americans into moving away from the pro-choice camp. Some pollsters, however, wondered if the Gallup results truly reflected a major shift in public opinion on such a controversial subject, given that other recent polling data has shown no signs of Americans becoming more conservative on abortion.
As it turns out, there is serious reason to question the sampling methods employed by Gallup for its May 7-10 survey. In eight previous polls taken by Gallup in 2009, the average party identification had been Democrats 35.4% and Republicans 27.1%, a difference of more than 8 percent. This includes Gallup’s most recent poll of April 20-21, which gave Democrats a 9 percent advantage. Yet in the poll with the pro-life results, the respondents were evenly split, 32%-32%. Because Republicans are more likely than Democrats to oppose abortion, this unusual division in party identification would skew the results in favor of “pro-life.”
Of course it is possible that the month of May did see a sudden shift from the Democrats to the Republicans, but this is not reflected in polls by other agencies. In addition, when pollsters ask Americans for more specific views about abortion, most respondents say they believe that abortion should be legal under certain circumstances, but not all. In fact, in the same Gallup poll that said that a majority of Americans are pro-life, only 23% thought that abortion should be completely illegal.
-David Wallechinsky, Noel Brinkerhoff
Abortion and Birth Control Combined Results (Polling Report)
On the Bouncing Party ID Numbers (by Jay Cost, Real Clear Politics)
New Gallup has PID Tied. Yep, It's an Outlier (by Charles Franklin, Pollster)
More About the Unbearable Lightness of Abortion Polls (by Ed Kilgore, FiveThirtyEight)
Is Public Opinion Changing on Abortion? (by Nate Silver, FiveThirtyEight)
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