In November, iMediaEthics tested Pew’s October poll results on trans fat: Pew’s phone poll (conducted by PSRAI) found 44% in favor of trans fats being banned from restaurants, while iMediaEthics’ November GfK web-based poll found 64% in favor.
iMediaEthics re-tested both polls in December to see if public opinion had actually changed that much, or if the large difference was because of the method of polling — phone versus internet.
Based on PSRAI telephone polling and GfK web-based polling (which uses The KnowldedgePanelTM), the iMediaEthics’ study confirmed significant differences between poll responses given on the phone versus those obtained on the Internet. CONT.
Andrew E. Smith & David W. Moore, iMediaEthics
See also: GfK responds to iMediaEthics’ doubt about its poll; iMediaEthics answers GfK response