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NullVoid » Research NullVoid » Research

Research

Blast from Past: ExtractBib.pl

Tuesday, January 21st, 2014 -- By ET

A number of years ago, I wrote a program to extract the right subset of bib entries for a tex file from a huge bibtex file.

Today I received the following email from Dr. Florian Kluge of Universität Augsburg, Institut für Informatik:

Dear Professor Zhang,

Some years ago I found your extractbib.pl script – it was a great alleviation
for me. Thank you for the gread work!
In the meantime, my requirements changed a bit, and thus I extended the script
to able to handle multiple .tex and .bib file.
I attached the extended version to this mail, please use/distribute it if you
like.

Best regards,
Florian Kluge

This is a delightful surprise. I’m very happy that my work could be reused.

I attached Dr. Kluge’s new script here, hopefully it will benefit more people.

Updated Script

 

Political Uncertainty and Corporate Investment Cycles

Tuesday, June 19th, 2012 -- By ET

I read this paper from Journal of Finance (2012 Feb issue).  It tells an interesting story: during election years, firms reduce investment expenditures by an average of 4.8% relative to nonelection years, across nations, controlling for growth opportunities and economic conditions.

The authors explained the observation with political uncertainty.  I wonder if more can be done on this. Does political uncertainty affect individual firms or the economy in general? Would these elections also affect end consumers/voters?  There seems to be a lot of interesting questions related to this topic.

Why SOPA is Bad to Innovation

Wednesday, January 18th, 2012 -- By ET

SOPA stands for Stop Online Piracy Act, which is a legislation introduced by the US House of Representatives. Websites like Google and Wikipedia believe this is Internet Censorship and it will cripple the Internet.

Wikipedia showed a blackout page today to protest, and it will last for 24 hours.

In my paper with Feng Zhu (You can download the paper from here.) published in June 2011 in the American Economic Review (AER), we studied the effect of blocks of the Chinese Wikipedia on incentives to contribute.

A direct effect is obviously that many people can no longer contribute to Wikipedia.

The following figure suggests that contributions from China reduced significantly after the block.

The bar chart further compares the contributions from different regions before and after the block.

An indirect effect is that people who were not directly blocked also reduced their contribution significantly. In the paper we estimate that the reduction in contribution from those who are outside China is more than 40% within the 4 weeks after the block.

The next figure shows the number of new contributors. It can be clearly seen that each block (shown in shaded areas) significantly reduced new contributors.

The lesson learned: information needs to be free. Legislation not well thought out may bring unintended consequences.

Best Birthday Gift

Friday, June 3rd, 2011 -- By ET

It was my birthday on June 1 (yes, the children’s day, that’s why I don’t get old).

My friend John was visiting, he was bored so dragged me to watch the Horse Race in Happy Valley.

The point is really not watching horse. We were busy checking the statistics of the horses and played a few hands. I typically don’t do gambling because I always believe it is a form of “stupidity tax”. This time, however, I played. Of course, we lost.

Just before we were ready to leave, I got the email (can’t imagine the days without iphone). It was the acceptance letter of my paper by Management Science.

So I guess this is the best birthday gift ever. I started working on that paper in 2003, then presented it in 2005. Presented it as my job market paper around the world (literally), and it won me quite a number of great job offers. However, it was such a long journey to publish it. It stayed at one particular journal for 18 months before I got two very irresponsible reviews.

Probably we were one of the first to write on the topic, when we first submitted it in 2006/2007 the reviewers could hardly understand what we were talking about. After several years of extensive study by many other colleagues, finally the value of the paper gets recognized. When we submitted it to MS in 2010, one of the reviewers said:”This is a very timely study to look at dynamic features of keyword auctions, while the majority of the literature still relies on static models.”

Some friends asked me if the reviewers knew the “inside information” of my birthday. I guess not, even if they do, it would be hard to coordinate so that the editors can send out the notification exactly on that day.

For the record, my dear reviewers, please do not wait to surprise me only on my birthdays. Surprise me now! Surprise me any time!

Blue Army Red Army

Tuesday, May 17th, 2011 -- By ET

My Social Graph on Facebook

Sunday, February 13th, 2011 -- By ET

Productivity

Friday, August 27th, 2010 -- By ET

I came across a senior professor in Statistics in the hall way. He noticed that I moved my office.

I told him that the new office has a window, and my research productivity increased by 5 times.

He then said:”Wonderful, they should have installed 2 windows for you.”

Hilarious!

German Publicity

Thursday, August 26th, 2010 -- By ET

This blog recently saw a big surge in the number of visitors from Germany. With a little tracing, I found the following website: http://www.handelsblatt.com/politik/wissenswert/studie-wie-wikipedia-markttheorien-widerlegt;2640653;0

The website is called “Handelsblatt Economy Newsletter” that reports “New trends in economics and business administration”.

It’s purely in German and the article specifically talks about the forthcoming AER paper Feng and I wrote about Wikipedia.

I used Google to translate the article, and it looks quite nice to me.

========Translated Article Below=========

LONDON. What a mistake. In the summer of 2002 reported the “Berliner Zeitung” as one of the first German media over the Internet Wikipedia – fascinated, but also skeptical: “But like the reservoir of knowledge also have large audiences and continually grow: In the near future it will not succeed, well, works of reference such as the Brockhaus outdo. “No six years later, told the Brockhaus publishing the end for the printed dictionary with – and Wikipedia now one of the most frequently visited Internet sites worldwide. Tens of thousands are working for free, voluntarily and without any fee.

A success story that brings economists provide explanations. Their traditional theories suggest that it would not even have the rise of the Internet lexicon may be. Why should rational individuals make the effort to write encyclopedia articles free of charge for an anonymous audience? Any Internet user can use the Online Encyclopedia, without himself contributes articles.

Thus, Wikipedia is what economists call a “public good” – an offer that will benefit all the people and by the use of which no one can be excluded. Classic examples of this are dikes and street lights. For public goods, so budding economists learn in basic, there is a big dilemma: There are strong incentives to freeloaders – to seize the offer without providing anything in return. The traditional economics postulates: the greater the number of potential beneficiaries, the more problems arise with free riders.

At least with Wikipedia is exactly the opposite is the case, shows a new study that appears in the upcoming “American Economic Review: The greater the number of potential readers, the more people are willing to devote their working hours for the online encyclopedia – probably because they draw mental satisfaction from the fact that their text be read by many others.

The scientists Xiaoquan Zhang (Hong Kong University of Science and Technology) and Feng Zhu (University of Southern California) have this effect after the example of the Chinese Wikipedia page. They use the fact that the government in Beijing has repeatedly censored the site due to politically unwelcome information. From October 2005, for example, were Internet users in China, the Wikipedia page does not call for nearly a year. By blocking the target audience of Wikipedia has reduced drastically over night. Million Internet users were suddenly excluded. For Chinese people in Taiwan, Hong Kong and the rest of the world, the page remained available, however.

What impact that had on the activities on the website? The researchers focused on the behavior of users outside the People’s Republic of China – people who, despite barring further access to the site and could change them. Zhang and Zhu use the fact that all changes are recorded in detail in texts on the Wikipedia page, and conceivably relate to the country in which the authors live. They compared the activities in Wikipedia immediately before and after the lock. They noted: With the start of the blockade itself have Chinese-language Internet users outside the People’s Republic of considerably less interest in Wikipedia – suddenly they wrote fewer new contributions and extended existing texts much rarer.

“The participation of authors is not blocked by the blockade decreased on average by 42.8 percent,” the economists note. The reason: The level of cooperation in Wikipedia procure satisfaction of the individual authors – researchers are referring to “social benefit”. “The shrinking group size reduces this benefit,” they write.

One indication of this is precisely the authors, where the social aspect of Wikipedia was very important and intensively romped in the discussion boards of the lexicon, wrote at the beginning of the barrier significantly less. “Our study provides empirical evidence that social effects may be stronger than the tendency to freeloaders,” the bottom line.

The study shows once again: economists make a mistake when they explain to the people to pure egoists – they can not explain many phenomena of real life properly.

Fixing CrossOver in Snow Leopard 10.6

Wednesday, August 18th, 2010 -- By ET

An update of the system broke my almost-perfect installation of Bakoma Tex in Mac OS X 10.6 through Crossover.

It took me a few months to suffer from this tragedy. Each time when I need to work with LaTeX, I need to load my Windows 7 from bootcamp. I tried to reset the Java Virtual Machine and so on, but it could not fix the problem.

Then today I thought about the error message it gave when I tried to open CrossOver. It says “can’t load ‘/system/library/perl/extras/5.10.0…”, so it strikes me that maybe it is Perl that needs fixing.

I went to /usr/bin to list perl versions:
/usr/bin$ ls -l perl*
lrwxr-xr-x 1 root wheel 9 Aug 18 10:50 perl -> perl5.10.0
-rwxr-xr-x 1 root wheel 86000 Jun 24 2009 perl.old
-rwxr-xr-x 1 root wheel 51200 Jun 24 2009 perl5.10.0
-rwxr-xr-x 1 root wheel 34816 Jun 24 2009 perl5.8.9
-rw-rw-rw- 34 root wheel 807 Jun 24 2009 perlbug
-rwxr-xr-x 1 root wheel 38307 Jun 24 2009 perlbug5.10.0
-rwxr-xr-x 1 root wheel 45068 Jun 24 2009 perlbug5.8.9
-rw-rw-rw- 34 root wheel 807 Jun 24 2009 perlcc
-rwxr-xr-x 1 root wheel 17983 Jun 24 2009 perlcc5.8.9
-rw-rw-rw- 34 root wheel 807 Jun 24 2009 perldoc
-rwxr-xr-x 1 root wheel 255 Jun 24 2009 perldoc5.10.0
-rwxr-xr-x 1 root wheel 254 Jun 24 2009 perldoc5.8.9
-rw-rw-rw- 34 root wheel 807 Jun 24 2009 perlivp
-rwxr-xr-x 1 root wheel 12309 Jun 24 2009 perlivp5.10.0
-rwxr-xr-x 1 root wheel 12304 Jun 24 2009 perlivp5.8.9
-rw-rw-rw- 34 root wheel 807 Jun 24 2009 perlthanks
-rwxr-xr-x 1 root wheel 45068 Jun 24 2009 perlthanks5.8.9

Perl 5.10.0 is a 64 bit version. So I downgraded the perl to perl 5.8.9 by the following commands:

sudo rm perl
sudo ln -s perl5.8.9 perl

Then it worked like a charm.

Traits of Successful Business Executives

Friday, August 13th, 2010 -- By ET

I’m doing some literature review for a paper of mine. I came across the following paper:

The Business Executive: The Psychodynamics of a Social Role

By: William E. Henry

The American Journal of Sociology, Vol. 54, No. 4, Industrial Sociology (Jan., 1949), pp. 286-291.

(http://www.jstor.org/stable/2770647)

It was written in 1949, and talks about the common characteristics of successful business executives. Typically I do not find these descriptive papers useful, but it is interesting to see how people in 1949 perceive what executives should do to be successful.

The paper listed the following personality patterns that are common for success:

    Achievement Desires
    Mobility Drive
    Idea of Authority
    Ability to Organize Unstructured Situations
    Decisiveness
    Strong Self-Structure
    Apprehension and the Fear of Failure
    Activity and Aggression
    Strong Reality Orientation
    Different Interpersonal Relations with respect to Superiors and Subordinates
    Broken Tie with his own Parents
    Dependency Feelings and Concentration Upon Self

That was a long list, if you check these on people we know, say Steven Jobs, you would probably be amazed how accurate these items can “predict” his success. I’m constantly suspicious of this type of work because they obviously miss the sample of failed cases. It could be the case that people who share these traits fail more, but due to the sample selection problem, we cannot observe them. What if some other factors are driving the success of these people, and they just learned to behave in this way (i.e., behaving in this way does not produce success.)?

This brings back to the argument of my paper: when people assume social roles, they behave according to the perceived traits of these roles. In many situations, the list of characteristics is a result of being successful, not a source of it.


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