I disagree with your use of &quot;prove&quot; when you wrote<p><i>Using &quot;elaborate statistical techniques&quot; one can prove pretty much whatever one wants to prove.</i><p>One may be able to massage data and create a nice looking chart to give an incorrect impression to unsuspecting people.  This does not constitute a proof and it certainly won&#x27;t pass muster with others who look at the same data and do their own statistical analyses.