title: What is 'gamma' parameter in OneClassSVM in scikit-learn Python?
body: <p>I am using OneClassSVM for novelty detection. Default gamma is said to be <code>1/n_features</code>, and <em>n_features</em> in my case is <strong>250</strong>. Changing gamma by 5 times or reducing by 5 times does not affect the prediction sensitivity significantly. What does gamma exactly represents and how can I effectively use it to tune the model (especially to increase positive predictive value)?</p>