Forever Learning

Forever learning and helping machines do the same.

Archive for June 2010

One Step Closer to the Cloud

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Because of the continuing lack of internet connectivity at my new address I’ve decided to move my website from my own server to the free space provided by my internet provider; thus bringing 5903 bytes of content one step closer to the amorphous blob of ‘teh interwebs‘ recently dubbed ‘the cloud’. You may now cheer.

Nothing ‘s changed; it just loads faster.

[Update after an inquiry from my colleague Willem: yes, the site now includes 20% more fluff.]

Written by Lukas Vermeer

June 21, 2010 at 12:27

Posted in Meta

Benford’s Law Revised

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After posting my previous article I started wondering why my transactional data contained a disproportional amount of twos. Something must be distorting the natural spread of first digits that Benford predicts. Later, while discussing this aberration with a friend, I finally figured it out.

It’s me. I distort the data. In fact, I distort the data every time I draw cash from an ATM.

Like most people I have habits. One of them is that when I use an ATM I almost always withdraw twenty euros (I find cash a nuisance and prefer plastic, so I withdraw as little as I can manage). This, almost deterministic behavior, is the reason why there are a disproportionate amount of twos in the data. It seems my previous conclusion applies to the data in more ways than one.

Real-life data is obviously not random data, and when you think about it there are perfectly logical explanations for this result.

If I remove ATM transactions from the original dataset the graph looks different. Still not exactly matching Benford’s prediction, but certainly a lot closer.

Tally of the first digits of bank transaction amounts excluding ATM transactions

Tally of the first digits of bank transaction amounts excluding ATM transactions

Update (april 2nd 2011): Code for this project is now available on Github.

Written by Lukas Vermeer

June 16, 2010 at 21:23

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