Monday, June 25, 2007

Brain Activity and Economic Judgment?

Just attended the keynote talk of Tom Mitchel at ACL 2007 in Prague. He described how the brain reacts when seeing a word or a picture associated with different concepts. For example, there are different parts of the brain activated when seeing a hammer (the word or a picture) and different parts when seeing an apartment. There seem to be different parts of the brain that process different concepts, so there is evidence that the "meaning" of a word corresponds to the activation of particular neurons.

I am wondering if similar things happen when someone is trying to judge the economic value of something. How do people act when seeing a bargain compared to seeing something that they perceive as expensive? Is there a similar activation pattern in the brain?

Update (July 2): I was reading the latest issue of Scientific American and I found an answer to the question above. Apparently, there is a related paper published in the January 26th issue of Science with the title "The Neural Basis of Loss Aversion in Decision Making under Risk" that discusses which parts of the brain get activated when someone needs to make a decision that will result in a future gain or loss. Interesting paper to read.

Monday, June 18, 2007

Are Publishers Making Themselves Useless?

No matter how nicely I try to format my camera-ready papers, occasionally I will get an email like this from the publisher:
  1. On page 2, top of column 1, you have a widow (last line of a paragraph at the top of a column), this is a bad break, please tighten the previous column or force a line over to eliminate this bad break.
  2. On page 2, bottom of column 1, there is an orphan, please tighten the previous material or force the head over to the next column. (The use of \vfill\eject placed before the head commmand will force text to the next page or column).
  3. Please make the body of the references section flush left/ragged right (not justified). This will eliminate letter and word spacing of references with urls (web addresses).
  4. On the last page, please use \vfill\eject before reference 19 to move more over to column two (2) and produce a more balanced last page. (This command is great for forcing material over to the next page.) Be sure that you have run bibtex, then cut and paste the references from your bbl file into your tex file.
I cannot understand why the author has to deal with all these typesetting issues, if there is publisher involved in the process. Isn't typesetting something that the publisher does? Given that I have submitted my LaTeX sources and all the necessary files needed to compile the paper, it is trivially easy to fix all these issues.

In the pre-digital age, a publisher would assign an editor to each accepted paper who would read the manuscript, fix grammatical and syntactic errors, typeset the article, and prepare a nice, readable version from the manuscript, which was either written by hand or typed in a typewriter. Today it seems that publishers want to push all the typesetting work to the authors, minimizing as much as possible the cost of production. Makes sense (economically).

However, as publishers push more and more of their responsibilities to the authors, they increasingly make themselves irrelevant. There is no reason to pay a publisher to prepare proceedings or even journals when the publisher does not even want to take care of the most esoteric publishing-related issues. In fact, there is no reason for a publisher to exist at all. What is the added value that a publisher offers? Open access and the web made already a significant part of the publisher's role obsolete; if publishers voluntarily make typesetting the task of their suppliers (authors), then they voluntarily make themselves a useless part of the workflow, ripe to be dropped completely in the near future.

Wednesday, June 13, 2007

Are Prediction Markets Efficient?

I was reading Fred Wilson's post about the information efficiency of the venture capital market.

While reading the posting, I started wondering whether prediction markets are efficient, according to the definition of Eugene Fama. In other words, how long does it take for a prediction market to incorporate all the available information about an event? Liquidity seems to be an issue for the existing prediction markets, preventing them from reaching equilibrium quickly. But if we had enough liquidity, how long would it take for humans to "agree" on prices that incorporate all the available information about an event?

Wednesday, June 6, 2007

Playing with Wikipedia

I was working with Wisam Dakka on a Wikipedia project, and I was puzzled by some Wikipedia entries that had really long titles.

The first one that I noticed was a term with 163 characters: "Krungthepmahanakornamornratanakosinmahintarayu
which redirects to Bangkok. I do not know if this is a prank, or a valid entry. (Update: It is a correct entry, according to the talk page of the entry.)

Then, I noticed another term with 255 characters:
"Wolfeschlegelsteinhausenbergerdorffvoralternwarenge wissenhaftschaferswessenschafewarenwohlgepflegeund sorgfaltigkeitbeschutzenvonangreifendurchihrraubgierig
which in fact is a valid term and the 255 characters is simply a shortcut for the 580 character entry :-)

Finally, there is a term with 182 characters:
that has Greek roots, and I will let you click to find out its exact meaning.

Also, these entries seem to trigger some buggy behavior on Google. If you do a web search for the above terms, you will find no web page with these words. However, Google returns a set of product matches on Google, none of which is really correct.

The joy of large-scale data processing!

Friday, June 1, 2007

Uses and Abuses of Student Ratings

I recently revisited an old posting from Tomorrow's Professor mailing list about "Uses and Abuses of Student Ratings". It is an excerpt from the book "Evaluating Faculty Performance, A Practical Guide to Assessing Teaching, Research, and Service" and lists a set of common problems in the use of student ratings for evaluating the teaching performance of a faculty member. I enjoyed (re-)reading the whole list, but I particularly liked these three items:
  • Abuse 1: Overreliance on Student Ratings in the Evaluation of Teaching ...
  • Abuse 2: Making Too Much of Too Little ... Is there really a difference between student ratings averages of 4.0 and 4.1? ....To avoid the error of cutting a log with a razor, student ratings results should be categorized into three to five groups ... Utilizing more than three to five groups will almost certainly exceed the measurement sophistication of the instrument being used.
  • Abuse 5: Using the Instrument (or the Data Collected) Inappropriately ... While we have 20 items on our ratings form ... only #7 really matters for making personnel decisions.
I am confident that if we read an academic paper that analyzes the results of a questionnaire in the same way that we currently analyze student ratings, the paper would have been considered naive (no statistical significance of findings, no control variables, use of a single instrument for evaluation, and so on). Unfortunately, it is does not seem likely that we will ever apply the same rigor when analyzing the student ratings forms.