Democracy for America

Supposedly, all three presidential candidates campaigned directly for people's votes.

http://2016.democracyforamerica.com/results

and there were protections in place to prevent a person from casting multiple votes.

http://www.democracyforamerica.com/blog/944-democracy-for-america-launches-2016-presidential-primary-endorsement-vote

As a "predictive" poll, it is useless... it's not representative of any larger population, and in *that* respect (its ability to product what some larger population thinks), it is as pointless as any of the typically maligned unscientific polls (easily recognizable by the lack of a margin of error figure). But that was not the purpose of this poll.

This result was precisely representative of what this particular group of people think... and that's what was used to generate the endorsement.