I am trying to build a classifier that would classify if a document is a document about sports or not. I have enough samples of sports document to train a classifier on, however I can't imagine how I would sample 'not a sports document' category as there can be anything - book, news article, resume, invoice etc. How would approach this problem?
I already tried training One class SVM classifier with my sample of sport documents, however the accuracy turned out to be awful - around 6%.
I also read about PU learning, do you think this is the way to go? Are there any other options?