There’s a new front-runner in Iowa, and — by popular demand — we talked about what it means in this week’s 2016 election Slack chat. As always, the transcript below has been lightly edited.

micah (Micah Cohen, politics editor): Harry and Nate, Ben Carson has opened up a clear lead over Donald Trump in recent Iowa polls:

What to make of this? Is this real? Does this say more about Trump or Carson? Much of the media is spinning it as the start of Trump’s demise.

hjenten (Harry Enten, senior political writer): I think the first thing we know — clearly — is that the Des Moines Register, Quinnipiac University and any other poll showing Trump not winning are garbage polls. They just have no class.

But if “real” means that Carson would win if the caucuses were today, then yes, it is real.

natesilver (Nate Silver, editor in chief): Reality is just a social construct, man.

hjenten: But this is the first time we can say Trump is definitely trailing in a contest that will be important in three months.

micah: Right. And Carson seems like just the type of candidate who could win Iowa.

natesilver: It’s definitely “real” in the sense that Carson’s lead is too large across too many polls to be a sample-size fluke.

hjenten: Carson has 36 percent of born-again/evangelical support. That looks like Santorum’s support did in 2012 in terms of what is needed to win. Carson is clearly connecting with the more conservative voters out there.

micah: So answer this question: Is this more about Trump or Carson? Or both?

natesilver: Both, but yeah — I think it’s more about Carson. Like Harry said, he looks like he’s winning the Huckabee/Santorum vote, and his profile is similar to a lot of past Iowa winners.

micah: So this seems like a localized Iowa thing and not necessarily evidence that Trump will fade nationally.

natesilver: Not necessarily. But there is an argument that it’s bad news for Trump.

micah: What’s the argument?

natesilver: That Iowans are paying more attention to the race than people elsewhere in the country, so they may be early adopters of trends we’ll see elsewhere. In other words, once Trump starts getting Iowa-type scrutiny in other states, he might fade.

hjenten: On average, Trump’s net favorability is +18 percentage points in the last four Iowa polls. That’s basically the same as it was the last time the same four pollsters were in the field (late August/early September), when it was +22. But there’s always been this sort of discord between Trump’s topline (horse race) numbers and his net favorability. We’d have thought, based off his net favorability, that he wouldn’t be leading the horse race.

Carson’s net favorability is +77 points! He’s much better liked. Net favorability isn’t always linked to doing the best in the horse race, but better-liked candidates generally do better. So I’ve always been skeptical of Trump’s numbers.

micah: Wait — but the point is Trump’s topline numbers have dropped in Iowa, but his net favorability hasn’t?

hjenten: To a degree, but Trump’s net favorability wasn’t good to start off with. What’s finally happened, it seems, is that as voters are paying more attention, the better-liked Carson has jumped in front. Trump could remain just as popular as he is now and still lose — because he isn’t that popular. Voters just need to pay attention to the other candidates.

natesilver: What’s interesting is that Carson doesn’t have all that much of a campaign operation in Iowa. Nor has he made all that many visits there.

micah: He’s on a book tour right now!

hjenten: Though Carson has always done fairly well in Iowa.

micah: Here’s the other thing: If you look at their trend lines in Iowa, Carson’s and Trump’s support mostly moved in unison until about a month ago, when Carson just shot up. So what happened?

natesilver: Well, as I’ve written before, I’m not sure that Trump and Carson have all that much in common. Carson seems to be a more familiar sort of candidate — high floor, low ceiling guy who appeals to evangelicals. Trump is more sui generis but vaguely resembles more secular candidates like Newt Gingrich who didn’t necessarily do that well in Iowa.

hjenten: Yes, this is the common mistake that folks make. They’re both outsiders, therefore they are the same. They aren’t the same.

micah: Another question: We got a string of non-partisan live-interview polls that found Carson leading Trump, but what did you make of that CBS News/YouGov poll showing them tied at 27 percent?

hjenten: Let’s get a little nerdy here shall we?

natesilver: YES.

hjenten: This has been one of the more interesting Trump phenomena; I believe Jon Robinson first discovered that Trump does better in non-live-interview polls. The belief being that people were afraid to admit they were voting for Trump to an actual person. But YouGov state polls, which are conducted online, really exacerbate this issue. So the question is whether people are afraid to admit they’re voting for Trump and/or whether YouGov simply doesn’t have the mechanism to get a sample that is representative of the primary electorates. You see this on the Democratic side, with Bernie Sanders doing significantly better in YouGov surveys than in other polls.

micah: Why can’t YouGov get a representative sample in these state polls?

hjenten: Because YouGov uses a volunteer sample. In general elections, if you have party identification, then you can just weight by that, but in a primary, you don’t. So other demographic factors become a lot more important. YouGov has taken some steps to control for that, but it’s fairly clear that some of these numbers are well out of line with other polls. Trump at 38 percent in New Hampshire? No other pollster besides YouGov has ever had him that high.

natesilver: Yeah, Occam’s razor is that if you take methodological shortcuts, then you’re probably in the wrong when you differ substantially from other polls. Plus, there’s some evidence that IVR (robopolls) and online polls herd toward traditional polls in the primaries.

I don’t want to completely rag on online polls — YouGov is better than a lot of crap like Zogby Interactive. And I’d trust online polls before IVR at this point. But still, the Iowa caucuses are a tricky thing to poll, and you have a lot of high-quality pollsters in the state who have a lot of experience with measuring the electorate in the state. They’re finding Carson ahead.

Plus, the idea that Trump voters would be ashamed to express their support for him in live-interview polls (some sort of a Bradley effect, in other words) seems speculative. It’s not as though Trump supporters are reluctant to make themselves heard. And it’s not as though voters in Iowa are reluctant to express “politically incorrect” positions.

What to make of Carson’s surge.

Farai Chideya, Harry Enten, and Jody Avirgan discuss.





Ben Carson is having a moment

micah: OK, so Carson is leading in Iowa — how does that affect the rest of the field? Is that good/bad news for anyone?

hjenten: I mean, it does show that some normal rules of GOP primaries still apply — that there can be a candidate who uses born-again/evangelical support to take a lead in Iowa. And that to me is good news for Ted Cruz or Bobby Jindal

micah: Isn’t it also better for Marco Rubio, Jeb Bush and John Kasich? Carson seems like the type of candidate who can do well in Iowa but not New Hampshire — isn’t it better for the establishment candidates to have that type of person win Iowa (short of winning the state themselves, of course).

hjenten: Agreed — Rubio is now tied for third with Cruz in Iowa. If Trump falls a little more (which seems completely possible), Rubio could take second in Iowa, and then boom! Hasn’t happened yet though.

natesilver: Before we talk about a return to normalcy, we should point out that Trump is still ahead in New Hampshire. What if Carson wins Iowa and Trump or Cruz or someone wins New Hampshire?

micah: I have no idea. Then you’re talking about a prolonged contest, right?

hjenten: To me, the more interesting question is what happens when it’s clear that Trump is no longer ahead everywhere. His net favorability argues that he should be far lower in the polls, but he is converting a much higher rate of people who have a favorable view of him into “votes.” If he starts falling in one place, does the entire enterprise just fall apart?

natesilver: This all seems a bit overeager. The media narrative about Trump is in disarray right now. If you look at the Iowa polls, he’s clearly fallen behind Carson. If you look at national polls, he’s still ahead (and, in fact, seems to have recovered some of the points he lost after the previous debate). So voters go back and forth between reading stories implying that Trump is doomed and those that imply he’s invincible. I wonder if that dynamic doesn’t help him a bit. It seems like he’s totally Teflon when the real story is more that there isn’t all that much news in the campaign and the media is over-interpreting noisy data.

micah: They can find both in one article if they read FiveThirtyEight. But IDK, it seems like you’re overthinking this: Trump has lost the lead in Iowa = bad for Trump. Not ruinous, but bad

hjenten: Trump has lost a lead.

micah: Yeah, Nate, it doesn’t seem that complicated.

hjenten: Yeah.

natesilver: He’s lost a lead, but that just creates more opportunities for “LOLZ you can’t predict Trump!!!!” later when he happens to get a sequence of good polls instead. Here’s what almost certainly would hurt Trump. Forget the polls. Finishing third place or something in Iowa would hurt Trump.

hjenten: Well sure.

micah: Does Trump need Iowa?

natesilver: Well, keep in mind that neither of us thinks he’s very likely to win the nomination in the first place. But unless he wins Iowa, I think it becomes even less likely.

hjenten: Yes, Trump needs winning. Trump is all about winning.

natesilver: You can’t spell “DONALD TRUMP IS A WINNER!” without T-R-U-M-P.

hjenten: That’s right. If I can, I’d like to quote myself from last night:

I love The Donald / His polls are so fantastic / When not, they're biased #odestoDonaldTrump2016 — Harry Enten (@ForecasterEnten) October 26, 2015

natesilver: Here’s the other thing: People seem to be assuming that we’ll be left with one “insurgent” candidate against a bevy of establishment candidates. For all we know, it could wind up being the reverse. Two out of the three of Cruz/Carson/Trump survive after Iowa and New Hampshire. Meanwhile, just one establishment-lane candidate is left.

hjenten: It could be Marco Rubio vs. the non-establishment. It could be, dare I say, John Kasich? Or it could be Rubio vs. Cruz vs. Carson. Again, we’re dealing with a small sample size with concern to primaries under the current system. It’s difficult to draw hard lessons from history.

natesilver: WHAT ABOUT JEB, HARRY? IS HE TOAST?

hjenten: I don’t think he is toast, but I think he’s in a lot of trouble. We can talk about Jeb! after the debate this week.

Check out our live coverage of the Republican debate.