26 January 2008 by John.

Until quite recently, astronomers thought that comets formed in the outer reaches of the solar system and then were drawn into highly elliptical orbits that pass near the sun. But samples collected from comet Wild 2 look more like they came from the inner solar system like asteroids. Maybe the outer solar system is more like the inner solar system, or maybe comets didn’t form where we thought they did.

For more details, listen to yesterday’s 60-Second Science podcast or read the Science Magazine article the podcast is based on.

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26 January 2008 by John.

Phil Haack gives his summary of a recent study on the benefits of test-driven development (TDD). The study had two groups of students write unit tests for their programming assignments. Students assigned to the test-first group were instructed to write their unit tests before writing their production code, as required by TDD. Students assigned to the test-last group were told to write their tests after writing their production code. Students in the test-first group wrote higher quality code.

The study concluded that code quality was correlated with the number of unit tests, independent of whether the test were written first or last. However, the test-first students wrote more tests in the same amount of time.

Note that students were assigned to test-first or test-last. Most programming studies are just surveys.  The results are always questionable because professional programmers decide their tools. So, for example, you cannot conclude from a survey that technique X makes progrogrammers more productive than technique Y. The survey may say more about the programmers who chose each technique than about the techniques themselves.

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