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RealClearPolitics HorseRaceBlog

By Jay Cost

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The Pennsylvania Polls Look Familiar...

Over the last few weeks, I have been intrigued by the movement in the Pennsylvania polls. It has had a striking resemblance to how the Ohio polls moved.

To confirm this, I graphed Clinton's lead in the RCP averages of the Pennsylvania and Ohio polls over the 21 days prior to each state's primary. The horizontal axis represents the number of days before the primary. The vertical axis represents Clinton's lead. The blue line is for Pennsylvania; the red line is for Ohio.

Clinton's Lead in PA and OH.gif

Clearly, the polls in both states have behaved similarly. The only significant difference is that Obama closed Clinton's lead much earlier in Pennsylvania than he did in Ohio. He moved to within 10 points 19 days before the Pennsylvania primary. This happened about 12 days before the Ohio primary. Other than this, Clinton's lead in one state has fluctuated almost identically with her lead in the other state.

We can check this via another direction. Let's graph Clinton's performance in Ohio and Pennsylvania against Obama's performance in both states. We'll keep red for Ohio and blue for Pennsylvania. We'll use triangles for Clinton and squares for Obama.

Clinton and Obama in OH and PA.gif

This confirms what the initial graph indicated. Here we see that perhaps Pennsylvanians have been a bit more undecided than Ohioans. However, as of yesterday in Pennsylvania, Clinton and Obama were essentially where they were at that point in the Ohio cycle.

What does this mean moving forward? I have no idea! Clinton could improve relative to Ohio. She could worsen. Yesterday gives us no assured indication of today or tomorrow. But it does put the Pennsylvania race to date in context.

Of course, it should not come as a big surprise that Pennsylvania and Ohio have behaved similarly to date. There are reasons to expect them to move in tandem. For those interested in an in-depth review of the Keystone State primary, I think this analysis I wrote last month is still largely valid. If you haven't read it already, you might find it worth your while.

-Jay Cost