title: Prediction variance and model bias of k-NN classifier
body: <p>I believe a lot of people have studied and are studying K-NN algorithm and I am one of them. </p>
  
  <p>I have just encountered a sentence saying like "For any given problem, a small value of k will lead to a large variance in predictions. Alternatively, setting k to a large value may lead to a large model bias.", I think it is straight forward to many people but not to me.</p>
  
  <p>If you already know what it means, please help me understand what it is.</p>