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October 27, 2005

Links, links, links.

The title is perhaps a modern variation on Hamlet's famous "words, words, words" quip to Lord Polonius. Some things I've read recently, with mild amounts of editorializing:

Tim Burke (History professor at Swarthmore College) recently discussed (again) his thoughts on the future of academia. That is, why would it take for college costs to actually decrease. I assume this arises at least partially as a result of the recent New York Times article on the ever increasing tuition rates for colleges in this country. He argues that modern college costs rise at least partially as a result of pressure from lawsuits and parents to provide in loco parentis to the kids attending. Given the degree of hand-holding I experienced at Haverford, perhaps the closest thing to Swarthmore without actually being Swat, this makes a lot of sense. I suspect, however, that tuition prices will continue to increase apace for the time being, if only because enrollment rates continue to remain high.

Speaking of high enrollment rates, Burke makes the interesting point

... the more highly selective a college or university is in its admission policies, the more useful it is for an employer as a device for identifying potentially valuable employees, even if the employer doesn’t know or care what happened to the potential employee while he or she was a student.

This assertion belies an assumption about whose pervasiveness I wonder. Basically, Burke is claiming that selectivity is an objective measure of something. Indeed, it is. It's an objective measure of the popularity of the school, filtered through the finite size of a freshman class that the school can reasonably admit, and nothing else. A huge institution could catapult itself higher in the selectivity rankings simply by cutting the number of students it admits.

Barabasi's recent promotion of his ideas about the relationship between "bursty behavior" among humans and our managing a queue of tasks to accomplish continues to generate press. New Scientist and Physics Web both picked the piece of work on Darwin's, Einstein's and modern email-usage communication patterns. To briefly summarize from Barabasi's own paper:

Here we show that the bursty nature of human behavior is a consequence of a decision based queueing process: when individuals execute tasks based on some perceived priority, the timing of the tasks will be heavy tailed, most tasks being rapidly executed, while a few experience very long waiting times.

A.-L. Barabasi (2005) "The origin of bursts and heavy tails in human dynamics." Nature 435, 207.

That is, the response times are described by a power law with exponent between 1.0 and 1.5. Once again, power laws are everywhere. (NB: In the interest of full disclosure, power laws are one focus of my research, although I've gone on record saying that there's something of an irrational exuberance for them these days.) To those of you experiencing power-law fatigue, it may not come as any surprise that last night in the daily arXiv mailing of new work, a very critical (I am even tempted to say scathing) comment on Barabasi's work appeared. Again, to briefly summarize from the comment:

... we quantitatively demonstrate that the reported power-law distributions are solely an artifact of the analysis of the empirical data and that the proposed model is not representative of e-mail communication patterns.

D. B. Stouffer, R. D. Malmgren and L. A. N. Amaral (2005) "Comment on The origin of bursts and heavy tails in human dynamics." e-print.

There are several interesting threads imbedded in this discussion, the main one being on the twin supports of good empirical research: 1) rigorous quantitative tools for data analysis, and 2) a firm basis in empirical and statistical methods to support whatever conclusions you draw with aforementioned tools. In this case, Stouffer, Malmgren and Amaral utilize Bayesian model selection to eliminate the power law as a model, and instead show that the distributions are better described by a log-normal distribution. This idea of the importance of good tools and good statistics is something I've written on before. Cosma Shalizi is a continual booster of these issues, particularly among physicists working in extremal statistics and social science.

And finally, Carl Zimmer, always excellent, on the evolution of language.

[Update: After Cosma linked to my post, I realized it needed a little bit of cleaning up.]

posted October 27, 2005 01:23 AM in Thinking Aloud | permalink