The Nebulas are voted for by the members of SFWA, the Science Fiction/Fantasy Writers of America, based on all the published stories from 2014. The Novelette category covers stories between 7500 and 17500 words.
I have only had time to read three of the six stories before the SFWA voting deadline. It’s Ferrett Steinmetz’s fault, really. His first novel FLEX released the first week of March and my reading time was all occupied with reading his book.