Monthly Archives: January 2010

Parameters and percentiles

The doctor says 10% of patients respond within 30 days of treatment and 80% respond within 90 days of treatment. Now go turn that into a probability distribution. That’s a common task in Bayesian statistics, capturing expert opinion in a

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Posted in Statistics

Economics rap

The debate between economists John Maynard Keynes and F. A. Hayek set to rap. Related post: The one thing to remember in economics

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Posted in Business

Weekend miscellany

Science Diamond oceans Plants put the bend in rivers State of biology data integration Programming Developer town (little individual houses as offices) .NET framework install base Evolution of a Python programmer How to recognize a good programmer Miscellaneous Crayola history

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Universal time

Universal time (UTC) is the same as Greenwich Mean Time (GMT), give or take a second. It’s essentially the time in Greenwich, England except it ignores Daylight Savings Time. The abbreviation UTC is an odd compromise. The French wanted to

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Statisticians take themselves too seriously

I suppose most people take themselves too seriously, but I’ve been thinking specifically about how statisticians take themselves too seriously. The fundamental task of statistics is making decisions in the presence of uncertainty, and that’s hard. You have to make

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Engineering in the open

From Herbert Hoover, mining engineer and 31st President of the United States: The great liability of the engineer compared to men of other professions is that his works are out in the open where all can see them. His acts,

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Estimating reporting rates

Suppose the police department in your community reported an average of 10 burglaries per month. You could take that at face value and assume there are 10 burglaries per month. But maybe there are 20 burglaries a month but only

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Posted in Statistics

Make something and sell it

I’ve run across a couple podcasts this week promoting the radical idea that you should sell what you make. The latest Entrepreneurial Thought Leaders podcast features David Heineimeier Hansson’s talk Unlearn Your MBA which he gave to a room full

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Posted in Business

How to compute the soft maximum

The most obvious way to compute the soft maximum can easily fail due to overflow or underflow. The soft maximum of x and y is defined by g(x, y) = log( exp(x) + exp(y) ). The most obvious way to

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Posted in Math

Ten surprises from numerical linear algebra

Here are ten things about numerical linear algebra that you may find surprising if you’re not familiar with the field. Numerical linear algebra applies very advanced mathematics to solve problems that can be stated with high school mathematics. Practical applications

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Posted in Computing, Math

Don’t invert that matrix

There is hardly ever a good reason to invert a matrix. What do you do if you need to solve Ax = b where A is an n x n matrix? Isn’t the solution A-1 b? Yes, theoretically. But that

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Posted in Math

The disappointing state of Unicode fonts

Modern operating systems understand Unicode internally, but font support for Unicode is spotty. For an example of the problems this can cause, take a look at these screen shots of how the same Twitter message appears differently depending on what

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Posted in Typography

Weekend miscellany

Math and aesthetics Beautiful architecture video.  No explicit math, but lots of math behind the scenes. Some math and some great images:  3-DSpirographs Advanced math with some pictures: algebraic topology books for download from J. P. May and Allen Hatcher.

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Spacecraft made from tape measures

The struts on the LightSail solar sail spacecraft are made from of Stanley tape measures. For details, listen to this episode of the Planetary Radio podcast.

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Technology history quiz

I was skimming through Big Ideas: 100 Modern Inventions the other day and was surprised at the dates for many of the inventions. I thought it would be fun to pick a few of these and make them into a

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