Republicans caucus differently than democrats:
http://www.latimes.com/nation/politics/la-na-iowa-caucuses-explained-20160131-htmlstory.html
How does it work?
Republicans and Democrats caucus differently.
After some organizational business and speeches, Republicans write down their pick for president and turn in their secret ballot.
Democrats break into groups according to their preference, plain for all to see. If a candidate fails to achieve the “viability” threshold of at least 15%, he or she is eliminated and supporters fall in behind another Democratic candidate. Or they can go home, though that is considered bad caucus form.
Yes, this is exactly how I understand it also.