Sunday, 25 March 2012

The sub zero stature of Global Alpha

In August 2007 Goldman Sachs experienced very substantial declines (in the region of 25%) in a couple of its own hedge funds, including the Global Alpha fund which has subsequently been closed down owing to further major losses in 2011 as reported here.

Goldman's CFO David Viniar was quoted in connection with the 2007 losses as follows:

“We were seeing things that were 25-standard deviation moves, several days in a row,”


To put the ineptness of this kind of quantification into context let us apply similar logic to the notion of heights of adult males and consider one who was 25 standard deviations below the mean height (since it is the left tail of the distribution which most likely caused the losses).

Evidence suggests that the mean height for an American adult male is about 5 feet 9 inches and the standard deviation is approximately 3 inches. To be 75 inches below the mean (i.e. 25 times 3 inches) of the mean height of 69 inches would mean that a suitably appropriate male, with similar characteristics to the moves alluded to by Viniar, would have a stature of a negative six inches.

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