But remember: It’s just one poll, and we talked to only 737 people. Each candidate’s total could easily be four points different if we polled everyone in the state. And having a small sample is only one possible source of error.

Can Florida’s Republican governor defeat its Democratic senator? We made 37724 calls, and 737 people spoke to us.

This survey was conducted by The New York Times Upshot and Siena College.

Hey, I’m Alex Burns, a politics correspondent for The Times. I’ll give you the latest reporting and intel on the midterms and take your questions from the campaign trail.

It’s generally best to look at a single poll in the context of other polls:

The men are fighting for a large Hispanic vote. Mr. Scott made frequent visits to Puerto Rico after Hurricane Maria, but Mr. Nelson won the endorsement of its governor, Ricardo Rosselló.

Other issues include health care — Mr. Nelson criticizes Mr. Scott for declining to expand Medicaid under the Affordable Care Act — and who’s to blame for a red tide outbreak on Florida’s beaches.

Mr. Scott presides over a rebounding economy, but he cannot run for a third term. After entering politics as a Tea Party favorite, he has shifted on some issues. He now advocates legal protection for immigrant “Dreamers” and limits on offshore oil drilling. This year he signed limited gun restrictions into law after the mass shooting at Marjory Stoneman Douglas High School in Parkland.

Mr. Scott, who if elected would be one of the richest members of the next Congress, put $73.8 million of his assets into a blind trust, but The Times found that there were numerous ways for him to have knowledge about the investments.

It’s one of the most expensive Senate races in the country and perhaps the most rancorous . In their only debate, Mr. Scott accused Mr. Nelson of accomplishing little in four decades in Congress. Mr. Nelson accused Mr. Scott of frequent lies and multiple conflicts of interest. The second debate was delayed because of Hurricane Michael and then canceled.

The nation’s largest battleground state has voted for the winner in every presidential election since 1996, and President Trump carried the state by just one percentage point in 2016. Polls indicate that the Florida Senate race could be close again.

is in his second term as governor of Florida; he became wealthy as a health care executive. 46% favorable rating; 45% unfavorable; 9% don’t know

is the incumbent, first elected to Congress in 1978 and the Senate in 2000. 40% favorable rating; 42% unfavorable; 18% don’t know

Each dot shows one of the 37724 calls we made.

If sampling error were the only type of error in a poll, we would expect candidates who trail by four points in a poll of 737 people to win about two out of every 11 races. But this probably understates the total error by a factor of two .

One reason we’re doing these surveys live is so you can see the uncertainty for yourself.

As we reach more people, our poll will become more stable and the margin of sampling error will shrink. The changes in the timeline below reflect that sampling error, not real changes in the race.

Our turnout model There’s a big question on top of the standard margin of error in a poll: Who is going to vote? It’s a particularly challenging question this year, since special elections have shown Democrats voting in large numbers. To estimate the likely electorate, we combine what people say about how likely they are to vote with information about how often they have voted in the past. In previous races, this approach has been more accurate than simply taking people at their word. But there are many other ways to do it. Assumptions about who is going to vote may be particularly important in this race. Our poll under different turnout scenarios Who will vote? Est. turnout Our poll result Our estimate — Nelson +4 People who say they are almost certain to vote, and no one else — Nelson +11 People whose voting history suggests they will vote, regardless of what they say — Nelson +3 People who say they will vote, adjusted for past levels of truthfulness — Nelson +7 Every active registered voter — Nelson +12 The types of people who voted in 2014 — Scott +1 The types of people who voted in 2016 — Nelson +1

The types of people we reached Even if we got turnout exactly right, the margin of error wouldn’t capture all of the error in a poll. The simplest version assumes we have a perfect random sample of the voting population. We do not. People who respond to surveys are almost always too old, too white, too educated and too politically engaged to accurately represent everyone. How successful we were in reaching different kinds of voters Called Inter-

viewed Success

rate Our

respon­ses Goal 18 to 29 2 9 0 3 7 1 1 in 41 10% 10% 30 to 64 2 0 2 4 6 4 3 9 1 in 46 60% 54% 65 and older 9 7 4 8 2 2 7 1 in 43 31% 36% Male 1 3 3 0 2 3 6 5 1 in 36 50% 46% Female 1 9 6 0 8 3 7 2 1 in 53 50% 54% White 1 6 0 6 5 4 3 5 1 in 37 59% 61% Nonwhite 1 5 3 7 5 2 6 7 1 in 58 36% 33% Cell 2 1 1 2 2 5 2 1 1 in 41 71% — Landline 1 1 7 8 8 2 1 6 1 in 55 29% — Pollsters compensate by giving more weight to respondents from under-represented groups. Here, we’re weighting by age, party registration, gender, likelihood of voting, education and region, mainly using data from voting records files compiled by L2, a nonpartisan voter file vendor. But weighting works only if you weight by the right categories and you know what the composition of the electorate will be. In 2016, many pollsters didn’t weight by education and overestimated Hillary Clinton’s standing as a result. Here are other common ways to weight a poll: Our poll under different weighting schemes Our poll result Don’t weight by education, like many polls in 2016 Nelson +4 Don’t weight by party registration, like most public polls Nelson +4 Our estimate Nelson +4 Weight using census data instead of voting records, like most public polls Nelson +3 Just because one candidate leads in all of these different weighting scenarios doesn’t mean much by itself. They don’t represent the full range of possible weighting scenarios, let alone the full range of possible election results.