Statistical Analysis of Iranian Election Data

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Sunday June 14, 2009 · 6:56 PM PDT

2009/06/14 · 18:56

Stochastic Democracy looks at recently released regional election data, but has not yet found any conclusive evidence of fraud. So far, the data seems to conform to Benford's law. However, the data seems inconsistent, and there are roughly 100,000 missing votes. Moreover, the percentage of "spoiled ballots" is much higher in areas where the opposition performed strongly.

More below the fold or at StochasticDemocracy.com

****Cross-posted at StochasticDemocracy.com ****

After looking a bit at the data from the last post:

The data seems to confrom to Benford's law, which means that if it was falsified, it was falsified in an "organic" way(For example, "every 3rd vote for the opponent goes to the incumbant). (The following graph looks at incumbant number of votes)

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With data:
Bin Frequency Freq Theoretical Freq
1 95 0.259 0.301
2 85 0.232 0.176
3 54 0.147 0.125
4 30 0.081 0.097
5 32 0.087 0.079
6 23 0.062 0.067
7 17 0.046 0.058
8 20 0.054 0.051
9 10 0.027 0.046

The data isn't entirely clean, the "total" number of votes is larger than the "valid" votes + the "invalid" votes. This leaves about 100,000 votes unaccounted for. This isn't extremely unusual, but, worth mentioning.

The number of invalid votes seems high in certain districts. In تركمن in Golestan for example, about 10% of ballots were declared invalid(This was a place where Mousavi did very well).

Furthermore, the percentage of spoiled ballots seems to be higher in regions where the opposition did better.

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Statistically, the correlations were statisticly significant (p<.001) for every canidate except Rezaee.

This could just mean that Opposition voters are younger and more prone to make mistakes, or it could imply voter suppression and tally bias. But still, invalid votes only made up 1% of ballots, and so even if this was the result of foul play, it wouldn't be enough to change the results.

All and all, We've yet to find convincing statistical evidence for fraud in the data. But we'll keep looking and post findings here. If anyone has any ideas or observations, please let us know in the comments or email us at dms at the-beach.net.

****Cross-posted at StochasticDemocracy.com ****

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Statistical Analysis of Iranian Election Data

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