A haver uma surpresa nas eleições americanas (i.e. derrota de Obama), discutir-se-á ad nauseam sobre o efeito Bradley. Mas no seu Margens de Erro, Pedro Magalhães adverte-nos para a possibilidade de parcialidade nas sondagens, “Evidence of Systematic Bias in 2008 Presidential Polling” (pdf):
We compared polls produced by major television networks with those produced by Gallup and Rasmussen. We found that, taken as a whole, polls produced by the networks were significantly to the left of those produced by Gallup and Rasmussen.
We used the available data to provide a tentative ordering of the major television networks’ polls from right to left. Our order (right to left) was: FOX, CNN, NBC (which partners with the Wall Street Journal), ABC (which partners with the Washington Post), CBS (which partners with the New York Times). These results appear to comport well with the commonly held informal perceptions of the political leanings of these agencies.
We also compared tracking polls produced by Gallup, Rasmussen, Hotline/FD, and the Daily KOS. Here again we found significant evidence of bias. Most notably, the Rasmussen and the Gallup polls were significantly to the right of the Daily KOS poll. A detailed analysis of the Gallup and Rasmussen polls also suggested the likelihood of short-term bias.
Our findings are preliminary, but given the importance of polling in America, they make a case for further research into the causes of and remedies for polling bias.
Nota: os resultados finais podem ser mais próximos que as sondagens sugerem mas a probabilidade de vitória de McCain é, mesmo considerando tal facto, muito reduzida.
Pedro Sette-Câmara
André Azevedo Alves
Carlos Guimarães Pinto
Helder Ferreira
Bruno Garschagen
João Luís Pinto
LA
Bruno Alves
Miguel Botelho Moniz
ruicarmo
Miguel Noronha
Elizabete Dias
António Costa Amaral (AA)
LT
Rui Oliveira
BZ
dos ∫antos
André Abrantes Amaral
planca12
rui a.
Rodrigo Adão da Fonseca
Adolfo Mesquita Nunes
Michael Seufert
Luciano
Carlos M. Fernandes
Maria João Marques
jtcb
Nuno Branco
elisabetejoaquim
filipeabrantes
Tomás Belchior
Bruno Gonçalves
Ricardo G. Francisco
Tiago Loureiro
Ricardo Campelo de Magalhães
Filipe Faria
Ricardo Arroja
Ricardo Lima
Eu estou curioso é do Bradley effect inverso: Negros que não têm coragem de dizer que votam McCain.
Comentário por lucklucky — Novembro 1, 2008 @ 19:51