Henry’s Weblog

Weblog 1.2 is released. It features a brand new documentation powered by Sphinx, including a rewritten tutorial and a more detailed reference manual. Thanks to Bastien Simondi for reviewing the documentation!

This new version also comes with a few bug fixes:

• Headers handled correctly with markdown
• Added more elements in Atom feed
• Display nothing instead of “unknown author” when there is no author
• Fixed date parsing and formatting
• Fixed escaping of UTF-8 entities

Get Weblog 1.2 on the download page.

Don't hesitate to ask questions about Weblog:

http://groups.google.com/group/weblog-users or weblog-users@googlegroups.com.

Somebody posted this link on reddit. It’s a logical quiz called “Einstein’s Intelligence Quiz”, it’s challenging, I had fun solving it. Try it; it should keep you busy 20 minutes or more.

This test is also known as the Zebra Puzzle. And there is no prof that Einstein wrote it.

At the top of the page and you can read:

[Einstein] said that 98% of the people in the world cannot solve the quiz.

I guess this sentence was added to challenge the reader, being in the top 2% of the world population is something most would proud of. Oh … this is also a typical example of doubtful statistic.

Prefixing a statement with “Einstein said …” makes it true

Attributing this sentence to Einstein is a deceptive way of making it authoritative.

“Einstein was soooo smart, this is certainly true!”

Sorry but Einstein was a physicist; not a statistician or a psychologist. He was not qualified to give such number. One could argue that the statistical background to calculate reliably such a number is basic, and that Einstein could have mastered it very easily. That may be true, but to support this number, a representative sample of the world population is needed. And you can’t give such a precise number with only 10 or 20 people.

For example when giving the test to 10 people the maximum failure rate you can have is 90%. If all 10 fail, then the failure rate is 100%, which is too high. If only 9 fail it’s 90%.

The get a rate of 98% you need at least 50 participants: 1 who succeeds and 49 who fail. Einstein was a loner, it’s unlikely he would have carried such an experiment.

I don’t believe Einstein pulled this number out of his ass either. He was a scientist, he knew that such number would be bogus without a proper evaluation. He would probably have said “Most people” instead of “98% of the people”.

Phony statistic

“OK, maybe Einstein did not say such thing. That does not necessarily make this number bogus.”

The number is bogus no matter who is behind it. There is no context, which raises several objections about its validity:

• There is no time limit to the test. I am not aware of any test measuring intelligence which does not have a time limit. This alone makes this number irrelevant.

• The world population’s intelligence tends to raise. Access to a better education system makes a big difference. So when was this sentence supposed to be true? If this test was “validated” in the 50’s, it’s clear that this number does not hold anymore. IQ test are “normed” every 20 years or so. To be relevant today this quiz should certainly be changed to make sure 98% of today’s world population fails it; or the number itself should be changed.

• The sample “98% of the people in the world” is dubious. Did the sampling really included a significant amount of people from poor regions of India, China, or Africa? Even now reaching these people is difficult. A sample composed mainly of Europeans and Americas is much more likely If anything was done to validate this “98%”.

• Of course there is no statistical details about the number. What was the margin of error or the number of participants for example? Today’s world is very found of numbers without context, such details are usualy omitted. They are nonetheless important, each omission of those statistical details should raise suspicion.

My guess is: this number was invented to stimulate readers to do the quiz and was not supported by any actual data. I wonder how many people successfully completed the quiz are proudly claimed to be in the top 2% of the world population.

Statistics are more and more important in today’s world. Lots of decisions are based on them. It’s still difficult to make good decisions based on good statistics, let alone those based on bad ones…

I am not a statistician, and my knowledge is limited. But aberrant numbers like this one are easy to spot. I recommend you to read How to Lie with Statistics, an excellent introduction to statistics for the layman. If you are a programmer I also the recommend Zed Shaw’s article Programmers Need To Learn Statistics Or I Will Kill Them All.

ssh-copy-id is a small script which copy your ssh public-key to a remote host; appending it to your remote authorized_keys.

$ ssh-copy-id root@192.168.1.1
root@192.168.1.1's password:
Now try logging into the machine, with "ssh 'root@192.168.1.1'", and check in:

  .ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

$ ssh root@192.168.1.1
Last login: Mon Nov  3 18:46:32 2008 from 192.168.1.32
OpenBSD 4.4 (GENERIC) #1021: Tue Aug 12 17:16:55 MDT 2008

Welcome to OpenBSD: The proactively secure Unix-like operating system.
# cat .ssh/authorized_keys
ssh-dss [removed] /home/henry/.ssh/id_dsa

This script is not shipped with OpenBSD. But it’s part of the Portable OpenSSH. It is self-contained, you just need to download and drop it in your ~/bin directory.

Download it from mindrot.org.

After my bad experience with the Cannondale Quick 4, I exchanged it with a Trek 7.3FX.

It is light and fast. Overall it feels much better than the Cannondale. The only problem is the uncomfortable saddle, but I will change it.

My old bike, a Kuwahara Fastlane, was stolen 1 week ago. It was a cheap bike, but it served me well during 1 year.

Immediately after I started looking for a new one. I visited my local bike store the next day and the sale person suggested the Cannondale Quick 4. It looked more a less equivalent to the other bikes in this price range, but it had a carbon fork and supposedly better components. Far from being an expert, I was impressed by the carbon fork and bought the Quick 4.

The first few days were disappointing. The bike was not as light and fast as I hoped. The shape of the frame was not exactly good looking; the down tube was big, and made it look a bit goofy. The big down tube made it harder to lock the bike to something. And the gearing behaved weirdly a couple of time.

Last Tuesday, while I was riding home after work, a pedal suddenly broke while I was pedalling. I instantly lost my balance and fell heavily in the middle of the road. There was no car around and I did not fell too badly. I was lucky, it could have been worst. In the middle of the traffic I would have been hurt badly.

I got to the bike shop the day after to exchange it. This bike is clearly not worth its price. Some components are plain bad. This is not a $100 bike; for this range of price the components should be able to resist more than one week. A fancy carbon fork is not worth risking your life. The Cannondale Quick 4 is crap. Dont buy it.