Both Cruz and Trump were within the margin of error for the polls, which was 4-5 percent. Cruz a little higher, Trump a little lower.
Rubio was the one who outperformed the poll prediction going beyond the margin of error.
Here's my source, for whatever the heck that's worth.
RE: Both Cruz and Trump were within the margin of error for the polls, which was 4-5 percent. Cruz a little higher, Trump a little lower.
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Trump’s lead the night before the caucus was 9 points.
http://freerepublic.com/focus/f-news/3391158/posts
Trump Leads Cruz by 9 Points in Iowa on the Eve of the Caucuses — 34-25%
Donald Trump 34%
Ted Cruz 25%
Marco Rubio 14%
Ben Carson 7%
Jeb Bush 5%
Rand Paul 3%
John Kasich 3%
Chris Christie 1%
Carly Fiorina 1%
Other 2%
Undecided 3%