Original sentence: However, their figures at other elections have been generally accurate.In the United Kingdom general election, 1997, then Cabinet Minister, Michael Portillo's constituency of Enfield was believed to be a safe seat but opinion polls showed the Labour candidate Stephen Twigg steadily gaining support, which prompted undecided voters to support Twigg in order to remove Portillo.They are usually designed to represent the opinions of a population by asking a small number of people a series of questions and then extrapolating the answers to the larger group
Edited sentence: However, their figures at other elections have been generally good, although they have displayed a fairly consistent tendency throughout the 1990s and the early years of the 21st century to overstate Labour support and understate Conservative support.In the United Kingdom general election, 1997, then Cabinet Minister, Michael Portillo's constituency of Enfield was believed to be a safe seat but opinion polls showed the Labour candidate Stephen Twigg steadily gaining support which prompted undecided voters to support Twigg in order to remove Portillo.They are designed to represent the opinions of a population by asking a small number of people a series of questions and then extrapolating the answers to the larger group