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More Evidence of Fraud in Iran: The Devil is in the Digits

- June 20, 2009

From my new colleagues “Bernd Beber”:http://www.columbia.edu/~bhb2102/ and “Alex Scacco”:http://www.columbia.edu/~als2110/:

bq. In the past week, analysts have scoured the results from Iran’s presidential election, looking for evidence of fraud. In an op-ed in today’s Washington Post online, we offer a different take on the problem. The key idea in the piece is that people are poor randomizers: When humans try to fake numbers, they leave traces of their activity in the data. For instance, psychologists have found that people choose some digits more often than we would expect in a sequence of random numbers.

bq. What distinguishes our approach from “Walter Mebane’s note”:http://www-personal.umich.edu/~wmebane/note18jun2009.pdf (discussed in a previous “Monkey Cage post”:https://themonkeycage.org/2009/06/mebane_on_possible_electoral_f.html) is that we look at patterns of _last_ digits in province-level vote returns. In a fair election, each number (0, 1, 2, etc.) should appear as often as any other in the last digit. But that’s not the case in the numbers from Iran: Among other things, wefind too many 7s and too few 5s. The deviations we find suggest there’s little chance the Iranian election results weren’t manipulated.

You can find the full op-ed “here”:http://bit.ly/wW6mm, as well as supplementary materials (including the annotated version of the op-ed and the data and code used in the analysis) “here”:http://www.columbia.edu/~bhb2102/.

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