title: What is the difference between RSE and MSE?
body: <p>I am going through Introduction to Statistical Learning in R by Hastie and Tibshirani. I came across two concepts: RSE and MSE. My understanding is like this:</p>
  
  <pre><code>RSE = sqrt(RSS/N-2)
  MSE = RSS/N
  </code></pre>
  
  <p>Now I am building 3 models for a problem and need to compare them. While MSE come intuitively to me, I was also wondering if calculating <code>RSS/N-2</code> will make any use which is according to above is <code>RSE^2</code></p>
  
  <p>I think I am not sure which to use where? </p>