Real Clear Politics has what it calls the "RCP" average for predict election results. It takes the last 5 polls and averages them together to get a consensus or predicted outcome.
This system is used frequently on Cable News and is often called the "poll of polls."
Below is a look at the RCP "polls of polls" margin of victory prediction and the actual results.
The results are from Primary states. Caucus states are not included so that we can have (as much as possible) an "apples to apples" comparison to the polling data for Pennsylvania.
There are no available "RCP Poll of Poll averages" for Primaries held in several states including Delaware, Mississippi, Vermont and Oklahoma. This was probably due to the lack of available polling completed for those states.
This left Real Clear Politics "polls of polls" available for 19 primary contests.
I separated the RCP results into the following categories.
RCP was extremely accurate (within 3 points) 42% of the time.
8 contests
New Jersey
RCP... Clinton +9.8
Results ... Clinton +7.7
New York
RCP... Clinton +17.2
Results... Clinton +17.5
Illinois
RCP... Obama +33
Results... Obama +31.5
Arizona
RCP... Clinton+ 6
Results... Clinton +8.8
Tennessee
RCP... Clinton +13.3
Results... Clinton +13
Ohio
RCP... Clinton +7.1
Results... Clinton + 10.1
Maryland
RCP... Obama 22.3
Results... Obama 23.5
Texas
RCP... Clinton + 1.7
Results... Clinton +3.5
RCP predicted the correct winner but the margin of victory (outside of 3 points) was wrong 32% of the time.
6 contests
South Carolina
RCP... Obama + 11.6
Results... Obama + 28.9
Virginia
RCP... Obama +17.7
Results... Obama +28.2
Wisconsin
RCP... Obama + 4.3
Results... Obama + 17.4
Rhode Island
RCP... Clinton + 9.7
Results... Clinton + 18
Massachusetts
RCP... Clinton + 7.0
Results... Clinton + 15.4
Georgia
RCP... Obama + 18
Results... Obama + 35.3
RCP predicted a margin of victory for the wrong winner 26% of the time
5 contests
New Hampshire
RCP... Obama +8.3
Results... Clinton +2.6
Connecticut
RCP... Clinton + 4.0
Results... Obama + 3.1
California
RCP... Obama + 1.2
Results... Clinton + 9.6
Alabama
RCP... Clinton + 1.2
Results... Obama + 14.1
Missouri
RCP... Clinton +5.7
Results... Obama + 1.2
Quick take home points.
It’s interesting that the RCP average of the best pollsters in the country (polls of polls) actually yielded the wrong winner (outright) a whopping 26% of the time or better than 1 out of every 4 contests!
I also found it interesting that of the 5 times the RCP predicted the wrong winner, 3 of the 5 mistakes (60%) involved Obama’s support being under-represented in polling.
The "Bradley effect" in today’s polling is very overrated. The media made a big deal about this following Clinton’s win in New Hampshire. But what happened in Alabama where Clinton was favored to win but Obama won by 14 points? Or in Missouri and Connecticut which do not have large African American Populations?
In the 6 contests were the RCP (poll of polls) has the winning candidates margin off by 3 points or more, (32% of the time) again it was Obama’s support that was underestimated in 4 of the 6 (67%) results. In fact only in Massachusetts and Rhode Island has Clinton exceed her RCP predicted margin of victory by 3 or more points.
The RCP polling average (Polls of polls) had the correct winner and the correct margin of victory (within 3 points) in 8 contests or 42% of the time. Amazingly in those contests, Hillary Clinton was the winner in 6 of 8 or 75% of the time.
Currently the RCP polling average for Pennsylvania is Clinton + 5.7.
Public Policy Polling and Survey USA should have new polls out Monday. Also Zogby is tracking the state daily and I believe Rasmussen will have another statewide poll out before voting on Tuesday.
You can find all of this information at realclearpolitics.com