Is Clinton's Pa. lead really 20 points?

People are questioning the results of the American Research Group's latest poll of Pa. Dem potential presidential primary voters as well as ARG's polling track record.

I posted today on ARG's latest results; and now I want to give you "the other side."

It comes from The Numbers Guy at WSJ. As with the ARG poll results this afternoon, I'll post without further comment.

The Numbers Guy begins - - -

A new survey showing Sen. Hillary Clinton leading Sen. Barack Obama by 20 percentage points in Pennsylvania comes from a polling firm with a shaky track record this election season.

The poll, which topped the Drudge Report on Monday afternoon (”shock poll”), was issued by American Research Group Inc. (ARG). In the poll, conducted on Friday, Saturday and Sunday, 57% of likely Democratic voters said they were supporting Sen. Clinton, compared with 37% for Sen. Obama. Just last week, each candidate received 45% in an ARG poll in the state. Other recent polls generally show a much smaller Clinton lead.

But there are reasons to question ARG polling numbers. In a polling report card of 2008 primary accuracy issued by a rival survey company, ARG ranked in the bottom half of more than three dozen polling firms, among 2008 primaries through late February. It also ranked near the bottom in another ranking of pollster accuracy at fivethirtyeight.com, a Web site that tracks the Electoral College. And, as I wrote last month, the widely tracked polling averages at the political Web site Real Clear Politics don’t include ARG numbers, because of concerns about transparency. Like they’ve been in Pennsylvania, ARG polls also were volatile in previous primaries, notably in Wisconsin, which saw a 16-point swing in just two days.

Dick Bennett, president of ARG, acknowledged his firm struggled in early primaries, but told me that its polls in later, big-state primaries have done well, citing California (the final poll showed a Clinton lead of four percentage points; she won by eight), Ohio (ARG had Sen. Clinton up by 14; she won by 10) and Texas (the poll had Sen. Clinton up by three; she won the primary by 3.5 points but appears to have lost the caucuses). According to Mr. Bennett, ARG’s stumbles in states such as Connecticut and South Carolina — where the firm understated Sen. Obama’s support — were due to underestimating the likelihood that first-time voters would go to the polls.

“In the tough ones, we’ve been close,” Mr. Bennett said. “As time has gone on, we’ve gotten much better.” ....

The rest of The Numbers Guy's report is here.