Some Democrats have cited an exciting-sounding statistic: Turnout broke the record set in 2008, when 287,542 people voted in the Democratic primary. This is noteworthy, but it is mostly attributable to the fact that there are more eligible voters in New Hampshire now than in 2008. The percentage of eligible voters who participated did not change much.

Also, because unaffiliated voters can participate in primaries in New Hampshire, it is tricky to compare cycles in which both parties have competitive races — meaning unaffiliated voters have to choose between two serious contests — with cycles in which one party has an incumbent whose renomination is a foregone conclusion.

This did not mean that breaking the 2008 record was insignificant — “a lot of people did come out to vote,” said Mia Costa, a political scientist at Dartmouth who studies electoral participation, “and there was a possibility that that wasn’t going to be the case, because that’s not what we saw in the last primary here” — but the numbers did not indicate unusual enthusiasm among Democrats.

The most interesting signals can be found in the demographic breakdown of the electorate.

Senator Bernie Sanders of Vermont, who won the primary by about 3,900 votes over former Mayor Pete Buttigieg of South Bend, Ind., was buoyed by very strong support among young voters. Exit polls show that Mr. Sanders overwhelmingly won voters under 40, while voters over 40 were split between Mr. Buttigieg and Senator Amy Klobuchar of Minnesota, and that dynamic may have been decisive, Dr. Costa said.

But the results do not appear to support one of Mr. Sanders’s biggest arguments for his “electability”: that he will bring a slew of first-time voters, formerly disaffected, into the fold.