title: Calculated field with forecasting data on Tableau
body: <p>It is possible to put the forecasting data into a table, so you can work with them?</p>
  
  <p>I need to show a number of how far our sales are from the tableau forecast, not just the graph.</p>
  
  <p><strong>UPDATE</strong></p>
  
  <p>I have two rows of data. </p>
  
  <pre><code>- PAST_DATA (2013 - 2014)
  - CURRENT_DATA (2015)
  </code></pre>
  
  <p>I need to forecasting the past data and then compare the forecast data with the current data to calculate the difference. It this possible?</p>