538 projects Trump 48, Cruz 41, for Feb. 1, 2016 Iowa Republican Caucus as of Jan. 28, 2016

1/28/16, "2016 Primary Forecasts," 538.com, fivethirtyeight.com

"The odds and polls for presidential primaries and caucuses, updated daily."

"Iowa Republican Caucuses"

"According to our latest polls-plus forecast, Donald Trump has a 48% chance of winning the Iowa caucuses.

Our forecasts don’t produce a single expected vote share for each candidate, but rather generate a range of possible outcomes, shown below. The range will be wider or narrower under certain circumstances: For instance, it narrows as the election gets closer. Our estimate of each candidate’s chance of winning the state is based on these ranges.

Not all polls are created equal, so our forecasts are calculated based on weighted polling averages. .  

The weights account for the quality of each poll based on its track record and its methodological standards. They also account for sample size and how recently it was conducted; recent polls are weighted much more heavily than older ones. Polls are also adjusted for house effects, which is a tendency to consistently show different results for a candidate than the average of other polls.
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For the Iowa Republican caucuses, we’ve collected 79 polls. Here they are, ranked by how heavily they factor in to our latest polling averages."...

Ten recent Iowa polls listed: 

PPP (Trump +8), 
Monmouth University (Trump +7), 
Marist College (Trump +7), 
Quinnipiac University (Trump +2), 
American Research Group (Trump +7), 
YouGov (Trump +5), 
Fox News (Trump +11), 
Douglas Fulmer and Associates (Cruz +2), 
Emerson College (Trump +10), 
Opinion Research Corp (Trump +11).

Images from 538.com 


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