The Investment Scientist

A story Technical Analysts won’t tell you

Posted on: November 9, 2009

This is a story shared with me by Larry Swedroe …

In 1959 Harry Roberts, of the University of Chicago, had a computer generate a series of random numbers that would have a distribution matching the average weekly price change of the average stock (about 2 percent).  Since the numbers were randomly generated, there was no pattern and therefore no knowledge that could be obtained by studying a chart of this nature. In order to create the illusion that his charts were those of particular stocks, Roberts placed a starting price of $40 on each chart. He then took a group of these charts to the leading technical analysts of his day. He asked for their advice on whether to buy or sell these unnamed hypothetical stocks. He told them that he did not want them to know the name of the stock since this knowledge might bias them. Each technical analyst had very strong advice on what Roberts should do but since the numbers were randomly generated the patterns were only in the minds of the observers. I am sure that you will never hear about this story from a technical analyst.

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Michael Zhuang is principal of MZ Capital, a fee-only independent advisory firm based in Washington, DC.


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