title: How to find difference between two Excel data series with differing timestamps on X-axis?
body: <p>How can I find the value difference between two data series on an Excel scatter graph, when both of the series have different timestamp entries for the X-axis? For example:</p>
  
  <pre><code>Series 1
  11:20:02    333
  11:20:15    332
  11:20:28    325
  
  Series 2
  11:20:04    992
  11:20:11    944
  11:20:18    932
  </code></pre>
  
  <p>Therefore I need to find the difference between the lines which have been plotted rather than the actual data-points... Is this even possible in Excel?</p>