Kj. Flannelly et al., Comparison of election predictions, voter certainty and candidate choice on political polls, J MARKET R, 40(4), 1998, pp. 337-346
Previous research has demonstrated the value of using 0-10 probability scal
es to predict election results. Three experiments are presented that confir
m the effectiveness of probability scales for political palling, and compar
e their predictions with those based on forced-choice scales. The results o
f these experiments show that using probability scales in telephone surveys
reduces the number of undecided responses by half, compared with forced-ch
oice scales, regardless of whether the surveys are conducted two weeks or s
ix months before an election. They also show that responses to the question
'Who would you vote for if the election was held today?' contain a degree
of uncertainty about future behaviour that is a source of error in politica
l polls which is not accounted for by sampling error. The results suggest t
hat this uncertainty increases the farther away in time the poll is conduct
ed from the day of the election.