Great Graphic: Obama and NYSE Composite

I spotted this Great Graphic on Business Insider. Joe Weisenthal got it from Chartist Friend in Pittsburgh.  It appears to use www.intrade.com data to assess the odds that President Obama is re-elected.  The lower chart is the performance of the NYSE composite.  

Joe's note sounded skeptical and so am I.  First, the note below the chart cites a strong correlation, but correlation is a mathematical relationship.  It cannot be eye-balled. 

Second, the conclusion does not follow from the evidence.   In fact, some observers attributed the stock market rally the day following the first debate to ideas investors hoped Romney would win.  

Third, although I too look at intrade.com, it is a starting point not the the final word.  For example, due to US regulations, it is difficult for Americans to participate.  The US presidential system, with its arcane electoral college, is complicated for Americans themselves, let alone many who live under parliamentary systems.  What follows from this is that national polls are misleading and frankly, beside the point.  What counts are electoral college votes and here Obama still looks to be the favorite.  There have been a few occasions in which one candidate won the popular vote and another the electoral college vote.  While such a scenario is possible then, it still seems unlikely.