The Iowa Caucus is done and although Clinton did win, she won by a razor thin margin of 0.4% of the vote. The Iowa Caucus is the primary election for that state and operates very differently from the primary elections that are held in most other states.
Statistical analysis of the Iowa Caucus shows that it has about a 43% success rate of predicting who will win the Democratic nomination. That's not a great success rate, but the Iowa Caucus is one of the first elections this year, so it gets most of the media attention in every presidential primary race.
Bernie Sanders is calling it a victory and rightly so. Even if he lost the vote, it was by a thin margin and the votes he did win came from a hard-fought campaign starting with very little money and very little name recognition. He was the underdog going against a well known politician financed by billionaires and large corporations in addition to the ordinary people who made contributions to her campaign.
Common Dreams has noted that Sanders was polling 6% to 68% a year ago. Back then his prospects were thin and few people believed that he was a viable candidate. The most recent Quinnipiac University Poll showed Sanders ahead of Clinton 49% to 46%.
Notably, Clinton is not doing so well with the generational divide. According to The Hill, Sanders enjoys an overwhelming lead of support among people under 45, 60% versus 31% for Clinton. This would suggest by getting out the vote with younger voters, Sanders could reach the tipping point for the nomination. This entire election could turn on the millenials, people born between 1980 and 2000. Closer scrutiny of the numbers suggest that the core of his support across America is from the younger crowd.
This is what happened in 2008, too. Younger voters came out in droves to secure a victory for Barack Obama. We may very well be on track for a repeat performance by younger voters. Judging by the numbers in New Hampshire, I would think so.