Approximity blog home
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Einstein's messy desk   23 Nov 08
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as I am such a chaotic person myself, I like it :-).

Third base: fast and easy date/datetime class   22 Nov 08
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The Ruby standard Date class tries to be all things to all people. While it does a decent job, it’s slow enough to be the bottleneck in some applications. If we decide not to care about the Date of Calendar Reform and the fact that the Astronomical Julian Date differs from the Julian Date, much of the complexity of Ruby’s standard Date/DateTime class can be removed, and there can be significant improvements in speed.

Updated gold silver watch   20 Nov 08
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Tom updated the gold silver watch.

Volatility has increased, esp. in the FX and commodities.

Check out the graphs .. dollar vs oil (expect the next bang here, but in the opposite direction).

Gold still looks pretty good in EUR and GBP.

Nice post by John Carter in the XP-ML.   21 Sep 08
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One of my favourite authors at the moment is Nassim Nicholas Taleb.

So he mostly speaks about finance, because that’s what he knows, but underneath he is mostly talking about statistics and risk. And that is what we all deal with.

His previous book "The Black Swan" in some senses wasn’t very useful… it can be abbreviated as "We are really Bad at prediction, much worse than you believe."

His latest essay is actually quite handy. It provides a map of where we are going to be startlingly Bad at predicting.

Many Agilisto’s will say, "Yip, he is right, thats why our practices work".

Others may look at Taleb’s essay and get an "Aha!" moment and finally realize why some of the Agile practices work.

He suggests you divide problems on the basis of moments of a random variable.

If your decision is a "yes/no" choice, it is simple. Will the project be finished by the 5th of December 2008?

If your question is based on the value of a random variable, it is more complex. What will be the completion date of the project?

If your question is based on a higher moment of a random variable, it is very complex. What will be the ROI of a project?

Then look at the nature of the randomness… Is it fat tailed, or well behaved?

For non-statistical types a probability distribution can be fat or thin tailed. The one you learned about in the stats course you have mostly forgotten was a thin tailed one. (Gauss / Normal distribution).

Odds on if you did any stats course they went on for hours about thin tailed distributions, because they can do the mathematics for them.

Unfortunately most real world distributions are fat tailed.

If you have a 1000 guys in the company, the average weight of employees is simply not going to shift by much if you employ the fattest guy in the world. (Fat guys come from a thin tail probability distribution.)

If you look at a 1000 random project case studies, the average project overrun is going to massively shift if you add the worlds largest project overrun.

ie. Things like food requirements for project workers are random variables from what Taleb calls "mediocristan".

Things like time to completion are from "extremistan".

So if divide your problems in to quadrants like this.…

 Simple Payoffs    |  Complex (Higher Moment) payoffs
 Thin tail distribution  Predictable      | Less predictable
 Fat  tail distribution  Less predictable | You're utterly stuffed.

Exercise for the Reader…

1) Catalogue the random variables in your work situation and categorise them as from mediocristan or extremistan.

eg. Time to complete an item of work - Extremistan

Programmer Productivity - Very high variance, but probably Mediocristan.

Security Risks - Extremistan. (No valid distribution on attack models, motivations etc.)

Exchange Rate fluctuations - Extremistan

Programmer Defect rates - Not sure. Maybe mediocristan for simple monothreaded programs. …

Welcome in service hell!   29 Aug 08
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Imagine this .. I buy a mac mini online .. all goes well .. I get a confirmation code and wait and wait an no parcel arrives .. then I login and see the order is cancelled. Do you think they would bother to email or call me to tell me that they cancelled the order? Thank you Apple.

Wikipedia saturated   11 Aug 08
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Adobe Flex developer wanted - remote or onsite   01 Aug 08
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Either as free lancer or permanently employed we need a Flex guru or an advanced Flex developer that likes challenges.

We have several projects in New York and Munich.

A small international team in an agile setting is waiting for you developing applications that scale to millions of users.

As usual, we care about experience, communication skills and simply the desire to excel and not page-long CVs.

If interested, please email me at armin at personifi dot com. Please no Word docs, only .txt or pdf or put it all in a simple email.

Next time we ask for some GNU Flex developers .. :-)

new energy blog   01 Aug 08
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Vimperator - gain back your time   20 Jun 08
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Thanks to Brenden for passing me this link.

First there was a Navigator, then there was an Explorer. Later it was time for a Konqueror. Now it’s time for an Imperator, the VIMperator :)

Vimperator is a free browser add-on for Firefox, which makes it look and behave like the Vim text editor. It has similar key bindings, and you could call it a modal web browser, as key bindings differ according to which mode you are in.

Now I need vim bindings for openoffice, so that I stop typing :w.

Six Degrees of Wikipedia   28 May 08
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Ever heard of the game Six Degrees of Kevin Bacon? If you haven’t, it works like this: Every actor gets a Kevin Bacon number. Kevin Bacon has a Kevin Bacon number of 0, actors who were in a movie with Kevin Bacon get a Kevin Bacon number of 1, actors who were in a movie with someone who has a Kevin Bacon number 1 get a 2, and so on (Everybody always gets the smallest number possible, so if you were in a film with two people, one with a 4 and one with a 6, your Kevin Bacon number would be 5).

The same idea could apply to the articles Wikipedia. Instead of taking "in the same film" as the relation, you can take "is linked to by". We’ll call the "Kevin Bacon number" from one article to another the "distance" between them. It’s then possible to work out the "closeness" of an article in Wikipedia as its average distance to any other article. I wanted to find the centre of wikipedia, that is, the article that is closest to all other articles (has minimum closeness).


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