Pew Research Center released new polling data showing GOP challenger Mitt Romney easing ahead of President Barack Obama among likely voters. There is little doubt Romney got a bump from his strong presidential debate performance, but he may have gotten an even bigger boost in the poll because of who was interviewed.
Chris Cillizza, who writes "The Fix" column in The Washington Post, noted that the latest Pew poll sample included 36 percent Republicans, 31 percent Democrats and 30 percent independents. No one knows for sure what the actual split will be in the election. However, Cillizza noted Pew's September presidential poll had a sharply different split — 29 percent Republican, 39 percent Democrat and 30 percent independent.
There may have been more than Romney momentum reflected in the two polls, he suggested.
In fact, samples are a critical factor in determining the accuracy and validity of polling results.
"If your sample doesn't reflect your target audience, then the results may be skewed," explains CFM Partner Tom Eiland.
Amid a hotly contested presidential election, polling results could boost one man's momentum and redirect the other's strategy based on faulty conclusions from a skewed sample.
Some poll results may be unquestionably true despite the sample. For example, the latest Pew poll shows two thirds of all registered voters say Romney won the debate. The percentage was even higher among independents, who many observers believe hold the key to winning the presidential election. The samples for independents were identical in both recent Pew polls.
There is a debate among public opinion research professionals over what the split will actually be among Democrats, Republicans and independents in the 2012 general election. GOP pollsters challenge whether Democratic turnout will be as high this year as it was in 2008, when Obama was elected. Democrats cite the registration of many younger people and Latinos, but there is no guarantee they actually will cast ballots.
In the end, polls are only as good as the assumptions that go into them and the samples that reflect those assumptions. The latest Pew poll suggests 5 percent more Republicans will vote than Democrats.
'It's a good habit," Eiland advises "to look at the sample before you look at the results and draw conclusions."