title: Accuracy Function
body: <p>I am doing a TS Analysis. What is the difference between these two accuracies:</p>
  
  <pre><code>fit&lt;-auto.arima(tsdata)
  fcast&lt;-forecast(fit,6)
  accuracy(fcast)             #### First Accuracy
  
  fit&lt;-auto.arima(tsdata)
  fcast&lt;-forecast(fit,6)
  accuracy(fcast,actual values)  #### Second Accuracy
  </code></pre>
  
  <p>How does the accuracy function work when I don't specify the actual values in the accuracy function as in the first case.</p>
  
  <p>Secondly what is the right approach to calculate accuracy?</p>