Author Archives: Liyun

About Liyun

M.Sc. Economics from Barcelona Graduate School of Economics.

Heckman's talk on inequity

Today, I was so luck to have enjoyed Heckman's speech. As usual, the information is attached here:

MOVE Distinguished Visitor Lecture
Speaker: James Heckman
Date: March 24, 2011

Heckman is well-known for the development of theoretical and empirical models of human development and lifecycle skill formation, with a special emphasis on the economics of early childhood education.

To be honest, I know Heckman because of his famous contribution to theoretical econometrics - actually, I just learned Heckman two-step estimation this month... Then he came here, and I got the chance to see the "real" version. Out of my expectation, he is such a good speaker! I concentrated on his speech for two continuous hours without a second to relax. OMG... I thought he was a technical guy - from the typical impression he should not care about anything else but math... However, I was totally wrong! He also works a lot on applications and empirical works which reflects the responsibility of a real economist. Like today, he talked about inequity. Although he was going to "sell" his academic idea, it was so good and so intuitive that can really convince you what is going on in the real world. So fresh, and comes to you with tons of inspirations.  Nice~

Tomorrow the more academic-targeted workshop will take place in UAB. Last time when I went to MOVE's workshop, there were only 20 people in a very big lecture hall and some of them were even sleeping... This time, from today's observation, I think there will be over 100 people tomorrow, and a big proportion of them will be brilliant researchers. It should be impressive. The basic info is attached here:

ICREA-MOVE Conference on Family Economics

Program Committee:Pierre-Andre Chiappori, Christopher Flinn, Jeremy Greenwood, Nezih Guner and James Heckman
Local organization: Nezih Guner
Date: March 25-26, 2011
Venue
: Campus de Bellaterra-UAB

It is so nice to enjoy this kind of high-quality workshop here in Barcelona. Fortunately, I think the school here, as well as those nice organizers, really encourage students to take part in these kinds of seminars. Therefore, most time I can just walk in the conference room and pick a seat without registering in advance. Thank them so much for tolerating me -_-||

Oh one thing at last. Yesterday dear Ghazala also offered a seminar on her own research, which focused on gender difference in the labor market:

LABOUR/PUBLIC/DEVELOPMENT FACULTY LUNCH
Date: 23/03/2011
Speaker: Ghazala Azmat and Rosa Ferrer (UPF)
Title: Gender Inequality, Performance Pay and Young Professionals

Since it was her, it had no reason to be not good.Meanwhile, the active audiences were impressive as they had always been.

Moreover, today there was also another Chinese professor who talked about his economic history research,

ECONOMIC AND BUSINESS HISTORY SEMINAR SERIES
Date: 24/03/2011
Speaker: Debin Ma (LSE)
Title: Rock, Scissors, Paper: the Problem of Incentives and Information in Traditional Chinese State and the Origin of Great Divergence

I did not have enough time for this presentation, since the time was a little conflicted with Heckman's speech. However, I stayed there for half an hour and got the basic idea what was going on. It seemed that he was talking about the popular issue "Great Divergence (中文相当于李约瑟之谜)", and reminded me the time when I read Kenneth Pomeranz (彭慕兰)'s book last year:

  • Kenneth Pomeranz, The great divergence: China, Europe, and the making of the modern world economy (Princeton University Press, 2001).

When it comes to China, I cannot just stand there and say "I do not care", right? But the Great Divergence is not only a question on China, but also for the whole world. Institution or technology? All of us are curious which one drives the economy to grow on earth...

A Piece of Note

Just a quick piece of note before the intensive exam time.

I did not really remember how many seminars I went in the past month... well, anyway. Here is just a note that I have been to Thijs' seminar:

Labour/Public/Development Lunch

Benedikt Herz and Thijs van Rens (UPF)

"Structural Unemployment"

That's really all.... no time to say more, and next week a plenty of interesting seminars are waiting... however, all the exams are waiting there as well... what a painful dilemma~~~

Physics > complex network > link prediction

It is a little funny that while I was trying to build the psychological-economic model in partner matching, two papers appeared in front of me, and they are all about link prediction:

  • Linyuan Lu y Tao Zhou, “Link Prediction in Complex Networks: A Survey,” 1010.0725 (Octubre 4, 2010), http://arxiv.org/abs/1010.0725.
  • D. Liben-Nowell y J. Kleinberg, “The link-prediction problem for social networks,” Journal of the American Society for Information Science and Technology 58, no. 7 (2007): 1019-1031.

Nowadays as an economics student, one important thing you can never overlook is math. That is why sometimes I feel that I am paying more attention to math instead of those economic thoughts. Yes we always stress economic intuitions. However, when it comes to the time problem, apparently math training acquires more time. More important, you may not able to build the entire economic intuition system only through lectures. Outside of the classroom is the place where you can really recognize the sense of how economics is related to people’s everyday life. Newspapers, street talks, and even TV shows may be more helpful.

Well… a little off topic. Today when I was listening to Thijs, suddenly a question not relative to any materials from that course came to my mind. What do we really care? Explanation, or prediction power? Of course they cannot be separated with each other. However, when it comes to prediction, it seems that people care more about the accuracy instead of why this or that method is working well. The best example may be the variety of methods of stock prices predicting. Once when I attended a statistics conference, there was someone who talked about his beautiful “triangle” prediction model of stock prices. For me, it does not make any sense. First, I’m not in the stock market, so I do not care; second, this kind of prediction methods are built above the cloud – there is no foundations which can even partly support the logic beyond the seemly accurate results. It may be unfair to attribute those meaningless methods to physicians – however, more of them studied physics before and they are somehow trying to transplant those solid physical theorems to economics, regardless the fact that economics is a branch of social science, which studies the (economic) functions of the society, the interactions among people and the fundamental reasons behind human behaviors. That is why whenever I see any model directly related to physics, I’m more careful about the economic implications behind the model: at least it should not be contra-intuitive.

Now myself is trying to borrow something from physics…. Obviously the first rule for me it to be as cautious as I can. In particular, I am trying to apply the link prediction idea to economic and social network analysis. Somewhat like the debate about reduced form and structural form in econometrics, I do not want to lose the micro foundations and economic intuitions behind the fancy model itself. It is easier if I just want to predict the result, but with consideration of internal and external validity, the model should be granted with more explanation power, which can conquer the difficulties originated from the complexity of the real society. Actually, I am fond of the name of this branch of science – complex network. How can we abstract simplicity from the complicated world? That may be the common question confronted by every single branch of science, no matter social science or hard/natural science. Without idea experiments in social science, how far can we go? It is really a difficult question to answer….

Anyway, hopefully I can find out a way to introduce link prediction ideas to my naive economic model. It is always interesting to work on the boundary of two different fileds, and you are tasting something new. However, the exams are coming so fast... need to focus on reviewing first.... Will update more later.

Barcelona under the wind

Today it rained a lot. I haven't seen this kind of heavy rain and strong wind here for a long time. Usually, in this kind of bad weather, I would not leave my warm room. However, it is the exam season now so there are a lot of works to do. Among all tasks, I have to go to campus and discuss the research proposal with one classmate. Actually we have found an attractive topic and are trying to combine economics and psychology as close as we can. Then, with the game I designed, no idea how to solve it... That is to say, some assumptions should be simplified in order for us to get a very good intuition about what is going on. It is a pretty interesting process, and we are really enjoying it.

Well... since I had to go to campus, I left my room in the afternoon under the heavy rain as normal. However, when I passed the twin building near Port Olimpia, the cloud above my hear shocked me. The last time that I saw cloud at such a close distance was last summer when I climbed the famous Mount Tai before came here. The difference is that, last time I was out of the city, so I was well prepared for the natural's magic; but this time, I was not expecting anything. Then, I could not stop myself from taking a turn to the opposite direction from school and go to the beach. The wind was really strong at that time, and the sea was not peaceful at all, compared to how it usually performs - actually I don't understand why the sea here is so peaceful. The waves were trying to show its anger, which had been stored for months. Although I had an umbrella in hand, it did not help at all. My shoes got wet, the mercyless rain drops hit me from every possible angle, and the wind blew as a crazy man...

I do not know which side of the sea I should love more. It was too peaceful as nothing would make a difference, so there would be no surprise. However, when it gets mad, I do not know whether I can stand the pressure. At least, I have seen both sides of the sea, and fortunately I did not miss it. That's fine than none.