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Echoing the thoughts of the Hotline's Chuck Todd, whose Outside Voices submission two weeks ago warned of the over-reliance on media polls in covering political campaigns, CJRDaily's Felix Gillette brings us the cautionary tale of the Zogby-Wall Street Journal poll. Gillette notes the attention given by local media outlets in Texas to results of this particular survey which showed Governor Rick Perry in potential trouble in his re-election bid. The Zobby-Journal interactive poll is tracking races in many of the important races in the country and often attracts attention. The problem? It's an interactive, self-selecting poll. As Gillette reports it:
For the mid-term elections, Zogby International has teamed up with the Wall Street Journal to create an interactive, Battleground States Poll (the entire methodology can be found here) which will be gauging (and perhaps shaping) voters' preferences in 18 Senate races and 19 gubernatorial races in the weeks to come.

When reached by phone last week, Cliff Zukin, a political science professor and polling expert at Rutgers University, suggests that journalists should generally be wary of any Zogby interactive poll.

"The Zogby stuff, on scientific grounds, is quite questionable," says Zukin. "Online, Internet, opt-in polling, where people volunteer to be respondents, doesn't really have a basis in scientific validity. There are two kinds of samples in the world. There are probability samples, and there are non-probability samples."

The Zogby interactive polls, says Zukin, clearly fall into the latter camp. "With probability samples, when everybody has a known chance of being selected, you can make pretty valid inferences about the population from which it is drawn," says Zukin. "You can't do that at all with self-selected surveys. That's a problem."

Public opinion polling today takes many forms, some less reliable than others. Many of the polls you may see sponsored by local television stations or newspapers are likely to have been conducted by automated calling systems rather than actual human beings. Reason – it's a cheaper method. Problem – it allows for more possibility of error. And the sort of self-selecting Internet polling is even more suspect by traditional survey standards. And the proliferation of these methods is one more reason to take all poll results with a hefty shaker-full of salt.
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