Published on greenfaucet (http://www.greenfaucet.com)
The Gambler's Fallacy
By Jeff Pietsch
Created 2010/03/17 - 12:08pm

It's more of a mathematical curiosity than anything else, but check out the odds of 14 successive up-days below, the record for which looks to get set by the SPY today. If that's not a pot of leprechaun gold for the bulls on this St. Pat's day, I don't know what is!

What really stood out to me in this quick study, is the dramatic bullish bias shown this last year with over 60% of days ending higher as compared to 53% since the SPY's inception seventeen years ago in 1993.

This strong bullish bias significantly increases the odds of successive runs over a "fair" 50/50 flip of the coin.  However, what are the independent odds of another up-day tomorrow?  Well—coins don't have any memory—do traders?

[1]

Note: Observations are non-overlapping.


Source URL: http://www.greenfaucet.com/traders-talk/the-gamblers-fallacy/45697

Links:
[1] http://2.bp.blogspot.com/_DGwK-zM3i_w/S6EHPNSixBI/AAAAAAAAApk/WLCooLSrVLQ/s1600-h/Gamblers.png