By Dave Anderson:
Quote of the Week on statistical geekery from Instaputz:
In the five months since he decided that the DJIA was a reliable indicator of Presidential and/or policy performance the benchmark index has risen by 37%. 37%! So tomorrow Glenn is going to write about how the Market God has bestowed upon our President the most confident of votes.
Noting that two things happen at the same time and assuming that causality exists between them is called spurious correlation. It is what stupid people do when they are getting ready to make really bad predictions - not just the bad " top to which
To wit: let's say I shaved my balls on Friday. Note that the market responded positively, only to once again decline as a vote of no confidence when the team of international observers (led by Jimmy Carter, former Canadian PM Brian Mulrooney, and the Dalai Lama) detected the growth of stubble.
The evidence is beyond dispute. My balls move markets....
The market is not rational regardless of how many business school professors pitched tents over its majesty as an arbiter of every political, social, and economic process. Remember, the market once told us that DrKoop.com was worth $45/share. It decided that theGlobe.com was worth $97/share (3 months later: a dime). It is not a parliament which issues meaningful votes of confidence and no confidence. Only a long view of market trends can provide useful (and retrospective, mind you) insights. Trying to use its day-to-day and week-to-week fluctuations as evidence of one's preferred version of current events is logical to the same extent that cavemen banging on drums to make the sun rise (and it worked - every day!!!) made sense.
The last paragraph is a decent defense of the Kinda-Sorta-Mostly-Eventually Efficient Markets Hypothesis that six days a week I believe in (the other day, I figure most things are rigged), but the bulk of this is an excellent exergis on stupidity near statistics.
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