The Hotel Club

Is it really such a good idea to own a home? Why not instead be a member of an exclusive club that owns hotel rooms in the world's most interesting cities?

My stuff is easy to move around, so why stay in one place, when fun is found elsewhere? A laptop, net access, clothes, good health, imagination and a loaded credit card. That's all you need.

Being a Bayesian can be Difficult

Is sample 1 smaller than sample 2?

Population Distribution

Sample n = 225

Prior and Posterior for mu

I assume data is generated from a normal distribution and additionally assume a normal prior for mu. Set mu_prior = 3.166 and sd_prior = 2.85, the approximate true mean and standard deviation for the population.

Back out the Bayesian test probability as 1 - pr(mu_1 < mu_2) from numerical integration.

MC Study: KS-test p-value vs. Bayesian Probability

Repeat the experiment n=100 times.

Kitchen Budapest: Hungary's MIT Media Lab

During my vacation in Budapest, I visited Kitchen Budapest, a bunch of cool, creative people doing art, inventing new technology and services. For example, combine a bunch of motion sensitive cellphones, a Mac, write some software and you have yourself a social mobile jamming session coming up. Kitchen Budapest and MobilJAM: I wish you luck.

Salaries in Hedge Funds

Rents are high in New York, but it seems that one group of people can make ends meet anyway.
At funds that manage $1 billion to $3 billion, people with just a few years of finance experience will make $337,000 this year, Mr. Zoia says, and those with five to nine years of experience will average $830,000, up 6 percent from last year. These estimates include analysts and researchers but not portfolio traders, who can make much more because they sometimes share in profits.

New York Times

Perception: Look at the Red Dots

Here is an exercise to think about visual perception.
  1. Open the visual applet
  2. Study the movement of the red dots
Now look at the explanation.

(Thank you, Illusion Forum)

Europeans Support The Common Agricultural Policy

EU's Common Agricultural Policy hurts the third world, but EU's population belive the current level of support is reasonable. In Eurobarometer's "Europeans, Agriculture and the Common Agricultural Policy" (2006) p. 22:

The evaluated importance of agriculture is reflected in evaluations of the EU budget for agriculture and rural development. Here more respondents believe the current share of the total EU budget given over to agriculture and rural development is sufficient (45%) compared to those who think it is either too high (16%) or too low (15%).

Don't expect real change in this area.

Why Have Sex? - About Evolution

Here is a demonstration of a simple evolutionary model driven by selection and mutation, no sex. If a creature is killed, it is replaced by a slightly mutated version of its killer. Created by Jeffrey S. Rosenthal, University of Toronto.

Evolution Applet

Marbled crayfish, an asexual species of crayfish, are doing very well around Madagascar as discovered by Dr. Julia Jones. Reproduction without sex can be more efficient in the short term, while endangering the species in the long term (from Economist ).

Early this year, biologists working in Madagascar were shocked to discover that Procambarus 'Marmorkrebs', the world's only known parthenogenetic decapod, had become established in brick pits and rice fields around the capital. I am working with colleagues at the University of Antananarivo (Jeanne Rasamy and Olga Ravoahangimalala) carrying out preliminary research on the rate of spread, the level of risk to biodiversity and agriculture and investigating possible ways of controlling the invasion.

Dr. Julia Jones

In 2005, Matthew Goddard from University of Auckland could report how his team had found evidence that sex speeds up evolution. They experimented with a sexual and asexual version of otherwise identical strains of yeast, monitoring their growth and survival across harsh and benign environments. It turned out that sex did not matter in benign environments, while the sexual strain did much better in the harsh environment.

National Geographic - Nature

Experience: Half Machine

Credits: mvejerslev
This week I visited the art collective Half Machine, who has a boat in Copenhagen. Cool. Reminded me of pictures from Burning Man festival.

Experiencing such generous creativity instills in me a sense of satisfaction and optimism.

Software Spots Key Community Participants

Researchers from Cornell and Microsoft did some interesting research on detecting key players in online communities.

Welser's group found that the most informative individuals – dubbed "answer people" – are also relatively taciturn, rarely participating in discussions heavily. They also tend to shy away from the "discussion artists" who dominate most threads.

Link (New Scientist)

National Geographic: Swarm Behavior

The classic magazine National Geographic is hosting an article about swarm behavior, ants in particular, and describe applications of swarm theory to human problems, such as that of business optimization.


Jesus Action Figures

Got to love this: Jesus action figures. Hallelujah.

If you work in a cubicle office environment, you are going to love the cubicle actions figures - "The Cubes(TM) - In this office, you're the boss!".

Link: Jesus (From Digg)

Link: The Cubes (Thank you, Damien)

Digg: Are You Human?

When signing up for Digg, you get to ask yourself the question: Am I human? Well, are you?

Machine Learning and Data Mining Tutorials

Andrew Moore, a machine learning and data mining academic that has inspired me a lot, has put together a tutorial on key topics in his area. The topics have titles such as "Decision Trees", "Probability for Data Miners", "Bayesian Networks" and "Non-zero-sum Game Theory".

One important area that is left out is that of ensemble methods, bagging and boosting. has a list of references to good papers on that subject.

Link (Tutorial)

Link (Ensembles)

Linking Pictures Based on Their Contents

The TED Conference this year displayed an amazing demo of a system that links pictures together based on their visual contents. It's hard to explain. The system creates a 3D model of the area where the pictures was taken and allows you to browse pictures in a truly unique way.

Link (Thank you, Intonaco)

McKinsey: The Business Case Against Tolerating Workplace Jerks

Employing jerks can cost your company. A jerk, understood as someone who insults and intimidates coworkers, can carry more indirect costs than one might think. This popular McKinsey Quarterly article explores the subject.

The Quarterly goes on to explain how SuccessFactors, a human resource management software company, has implemented a no-jerks policy.


PEW Survey: "The Daily Show" Watchers More Knowledgeable

PEW Survey finds that American watchers of "The Daily Show" and "Colbert Report" perform better at such tasks as naming the current Vice President. FOX News watchers were the worst performers.


Wal-Mart, Publix: Happy Customers, Profitable Customers

Wal-Mart is battling against a smaller competitor, one that has very satsified customers.
Publix has ranked number one out of supermarkets on the American Consumer Satisfaction Index, published by the University of Michigan, since it began 14 years ago, whereas Wal-Mart ranks last. Publix employees have a reputation for going out of their way to please customers—testimony to the motivational power of employee ownership, perhaps. Publix employees put your shopping into bags, take it to the car and refuse tips—unless you offer more than once. They own 31% of the firm through an employee share-ownership plan, making Publix the largest employee-owned company in America.
Economist (paid registration required)
So, Publix has satisfied customers, but is is profitable? When it comes to groceries, Publix profits are 40% higher than Wal-Mart's. Return on average equity: Publix 24%, Wal-Mart 21%.

The employee stock plan puts it in the same category as Starbucks, another company with satisfied customers. Good luck, Publix.

GG Genforening

Tid: Lørdag d. 2. juni kl. 16.00

From GG

Kære ex-GG'er,

kom til København og mød dine gamle gymnasiebekendte. I skrivende stund har 10 meldt sig til, mens flere måske kommer.

Dagens program

kl. 16.00 - 19.00 Drinks og snak på Hotel Fox, som ligger på Jarmers Plads 3
kl. 19.15 - 22.00 Spisning på restaurant, nærmere detaljer følger
kl. 22.00 - ? Efter temperament går man videre i byen

Der vil være mulighed for overnatning hos flere lokale. Niels har to sovesofaer der endnu ikke er reserveret.

Hvis du kommer fra Jylland med tog, så påtænk at bestille hos DSB i god tid. Måske er der en Orange-billet.

De bedste hilsner - Tina, Tine, Morten og Niels

Radical Transparency

In the article "The See-Through CEO", Clive Thompson for Wired Magazine argues that radical transparency in a company can be a source of competitive advantage. One mechanism behind this is Google, since it can be thought of as not just a search engine, but rather a reputation management system.

Animation of World Statistics

Very cool animation showing the evolution of life expectancy, gross national product per capita and population size. Press play in the bottom.

Best Gadgets for Travelers

Adam Baer, a seasoned gadget reviewer, recommends the best gadgets for travelers. A Leica digital camera, a Sony laptop and few other cool items. These recommendations are difficult to get from mainstream electronic stores, because the mainstream is unwilling to pay for elegance.


Open Source Economics Journal

The Kiel Institute has launched an ejournal on economic topics. Quoting the webpage:
"[The journal] adopts a “Linux approach” to publication, viewing research as a cooperative enterprise between authors, editors, referees and readers."

Political Parties and The 0.02 Threshold

Here's a riddle. Suppose you have formed a new political party and you want to assess the voter sentiment with respect to electing your party. Your party has to get at least 2% of total votes to enter. How many randomly selected respondents would you need to sample to draw the correct conclusion with 95% confidence?

The answer depends on the true proportion in the population, your required significance level and the statistical properties of the binomial distribution.

The figure above shows the minimum respondents you would need to sample, as a function of the true population proportion. If the true proportion is between, say, 3.5% and 4.0%, you would need to sample around 1000 respondents, before a statistician using a one-sided 95% confidence band would announce your party a viable proposition.

You can go about this in a dynamical fashion. Sample 500 respondents. If the mean proportion is below ~4.7%, then sample another 500. If the new calculated mean stays above ~3.7% you are fine.

Self-organizing Conferences

The author of "Thinking in C++", Bruce Eckel, writes about a conference methodology for self-organizing conferences.
What's the best thing that happened at the last conference you attended? It's very likely that you'll remember one or more "hallway conversations," or perhaps a "Birds-Of-A-Feather" session. An OpenSpace conference creates that experience for the entire conference, by ensuring that you are always having the most interesting conversation possible. The emphasis is on discussion, instead of listening to eyes-forward presentations.
Bruce Eckel

The Wizards of Buzz

"A new kind of Web site is turning ordinary people into hidden influencers, shaping what we read, watch and buy." A Wall Street Journal article about how social websites compete with traditional media.


Startupping - A Community for Entrepreneurs

A new site to support internet entrepreneurs. An interesting post reports on the experience gathered from a group of seasoned entrepreneurs.

Link (Thank you, Slashdot)

Corruption and Inflation

Transparency International publishes the Corruption Perceptions Indicator by country. IMF publishes measures of inflation. Are the two measures related? The figure below is based on 2006 data.

The blue line is a local regression fitting method. In this context it can be interpreted as a variant of a moving average.

London Exhibition Game Show

What a joy to once again meet the games of my childhood in this London Exhibition. Favorites: Bubble Bobble and SEGA's Bomberman.

Social Networks in Business

Tools to examine and map social networks and dynamics among company employees, expertise and hierarchy would be helpful to senior management in many larger companies. Trampoline Systems did an interesting project relating to this, using data such as email communications.


PhD Defense

My PhD defense will take place on the 16th of March 2007 at 14.15 in Aarhus.

Where? Aarhus University, Auditorium 025, building 1324.

(marked in red)


Wish me luck.

Qutb About the West: Dishes More Important Than Religion

I love my dishwasher. Sayyid Qutb, a radical islamic scholar, think I should care more about my soul. Here is what he concluded after having lived in USA 1948-50, citing Lawrence Wright:
Qutb saw a spiritual wasteland, and yet belief in God was nearly unanimous in the United States at the time. It was easy to be misled by the proliferation of churches, religious books and religious festivals, Qutb maintained; the fact remained that materialism was the real American god. ‘The soul has no value to Americans,’ he wrote to one friend. ‘There has been a Ph.D. dissertation about the best way to clean dishes, which seems more important to them than the Bible or religion.’ Many Americans were beginning to come to similar conclusions. The theme of alienation in American life was just beginning to cast a pall over the postwar party. In many respects, Qutb’s analysis, though harsh, was only premature.
Lawrence Wright, The Looming Tower
(Thank you The Bos'un Locker)

I prefer a society with clean dishes, anytime. There is a number of interesting articles about Qutb and his meeting with Western civilization.
  • Berman, Paul "The Philosopher of Islamic Terror" New York Times Link
  • Drehle, David von "A Lesson in Hate" Smithsonian Magazine Link
  • Potts, Rolf "The Tourist Who Influenced the Terrorists" Vagablogging Link
  • Siegel, Robert "Sayyid Qutb's America" National Public Radio Link
  • Wright, Lawrence "What Turned Sayyid Qutb Against America?" History News Network Link

Online Book: Dive Into Python

As my great grand-dad always said, "Son, life has taught me that you only need two tools in life. Python and C++". He was right. Learn Python using this online book.