It was really my honor to participate in these two conferences and deliver presentations to the audience. My talk was focused on experiments in social networks, and some consequent analysis in R. As the conferences were in China, I talked in Chinese throughout. Social network is a hot topic nowadays, but experimental methods are still at the beginning stage. With social learning models, we found out a good way to test the network effects with randomized experiments.

It was also my great pleasure to meet famous scholars worldwide. In the complex network conference, a lot people from physics and computer science brought my with fresh knowledge and inspirations. In the R conference, we invited so many experienced useR and exchanged our experience of using R. It is always good to feel that many people are enjoying the convenience of R and are happy to play with data in numerous fields.

At last, here are the slides I used to assist my presentation. Sorry but they are in Chinese…

DOWNLOAD:

slides_network_experiments_R.pdf

In terms of teachers, as the timeline goes, Lugosi, Ghazala, Thijs/Gino, Massimo/ Larbi, Davide…and more. I have enjoyed so many great courses despite some disappointing ones. Lugosi reconstructed my confidence in math – at least I can survive in real analysis! Thijs taught me more beyond his course materials – how to think, how to analyze real world problems, how to develop research ideas (hopefully I was not so annoying at that time…) and how to be patient. Interestingly, after macro, I picked micro II instead. You can say it was a turn, but in fact my ultimate goal of studying economics, ideally of course, is to link micro and macro more close to each other Massimo Motta was so amazing – clear about the course materials and patient with my random emails… I owe him a lot of thanks. Davide Cantoni, well, do I still need to mention his name any more on this blog? Economic history will stay as one of my best memory ever. Oh how can I forget development econ? I have learned so much from Ghazala~

Regarding papers, this year I have worked with several great Barcelona GSE colleagues to develop research ideas and formalize the frameworks. One on romantic relationship formation (partner matching) with Hrvoje Stojic who was so good at psychology and micro/behavior econ; one on social network and its applications to public health issues with Mahesh Karra, who served as an expert from the health perspective; last one by myself on economic history which talks about the financial innovation in historical China…plus another one oriented by a friend from another continent… The first half of this year was fully filled by papers and research inspirations. Although we could not finish each of them comprehensively and they look more like research proposals, the basic ideas show how much we have thought, exchanged ideas and challenged ourselves. In addition to the knowledge gained from classes and professors, the experience of cooperating with other talent people has also brought invaluable growth to me.

I am not sure what I am going to do in the second half of this year. This year started with a dismal situation, and sometimes it was pretty difficult for me to stand up after pains, finally time recovers everything. I will make a choice soon once I am back in China and meet necessary people to decide my future’s directions. Things are going as always, and after the journey only beautiful moments will stay as precious memories. After experienced the difficulty of life, I have realized how important it is to look ahead to the future. Growth is always an exciting process.

CREI-CEPR Conference on Institutions and International Capital Flows

As the usual CREI-CEPR style, it was pretty macro. I went for the first two in the first day:

Financial Regulation, Financial Globalization and the Synchronization of Economic Activity

and

The Flight Home Effect: Evidence from the Syndicated Loan Market During Financial Crises

Macro, finance and econometrics… this combination defines my feeling – could not really understand many things. Yes, in some sense these topics are interesting, and financial crisis is worth paying attention to, but to what extend are those researches replicable…

Oh, one point I should mention here. The second one mentioned the “flight home effect”, which was a new term to me. As operators of modern financial system, and one industry, the banks always attract special focus…It was nice to know their operations and some associated phenomena

Cover:

First and foremost, here is the special-designed cover for this project. Well, it is not so good (perhaps economics has killed most of my design cells in my brain, sigh), but uniquely related to our project.

The graph is not any random one, but the one generated for this master thesis! On the back side of the cover there is an explanation:
And, yes, let’s enlarge part of it and have a look at the links!

Yes, the illustrations are both based on real social networks. The front one is a social network graph constructed from a real SMS network; the back one reflects the co-authorships among economists affiliated to BGSE/UPF. They look like blooming flowers, right? How wonderful and beautiful information is!

Download:

The simulation part of this paper with several interesting graphs is available to be downloaded here: Master Project -_simulations.pdf

Summary:

After all, I would like to summarize and introduce our project briefly.

In one sentence,  it is a nice combination of social network theories and public health issues (HIV/AIDS), and we construct the analysis both from the theoretical (network learning)  and empirical (network estimation) angles.

Title: Expectations and the Social Network: Modeling Health Risk Perception among U.S. Adolescents

Author:  Liyun Chen and Mahesh Karra (Barcelona Graduate School of Economics and Universitat Pompeu Fabra)

Abstract:

This study aims to examine the determinants of HIV/AIDS risk perceptions and resultant sexual behavior among adolescents. We investigate the learning and decision-making process through which teenagers may update their risk beliefs, and argue that social interactions play an important role in understanding both phenomena. In particular, we hypothesize that social networks and peer risk perception of HIV/AIDS directly impact respondent risk perception and, consequently, risk behavior. We propose a theoretical framework in order to identify the mechanisms through which individual risk perceptions may respond to peer attitudes and social beliefs. Using friendship network data from the National Longitudinal Study of Adolescent Health (Add Health), we design an empirical strategy and test these channels. We conclude that many determinants of risk behavior are unobserved and may simultaneously affect both perceptions of risk and the size, composition, and selection of individuals’ social networks, particularly in the case of HIV/AIDS risk among teenagers. Social networks may have significant and substantial effects on adolescents’ AIDS risk perceptions; thus, in order to fully understand the dynamics and diffusion of behavioral change in response to AIDS, it is essential to incorporate the necessary network effects. Any network interactions are likely to have a substantial impact on the course of the HIV/AIDS epidemic and the magnitude of its consequences, particularly among the youth; these effects should consequently be taken into consideration when devising effective, targeted policy interventions.

Moreover, this time my co-author is pretty ambitious, and we are expecting these following policy implications:

Although our approach may show some promise in establishing the role of social network analysis in sexual health policy and advocacy among the youth, there are still many operational and methodological barriers which may confound any potential health intervention’s true network effect. Nevertheless, any findings are of central importance for understanding the spread of HIV/AIDS because they reinforce that social interactions constitute important determinants of how adolescents and youth communities develop strategies for coping with the disease. In particular, this study hopes to show that social networks exert significant influences on risk perceptions and the probability of adolescent communication about HIV/AIDS risks, and that these effects are in addition to any programmatic interventions that disseminate knowledge about the disease, provide access to sexual health services, and advocate changes in sexual behaviors. Moreover, we see that social networks are also likely to amplify program efforts aimed at increasing teenagers’ awareness of HIV/AIDS and their assessments of
their own risks. Any network interactions are likely to have a substantial impact on the course of the HIV/AIDS epidemic and themagnitude of its consequences, particularly for the youth; these effects must therefore be taken into consideration when devising effective, targeted interventions.

Overall, the cover looks like…a book? Haha. Otherwise it won’t have a cover

“Teaching to the Tests: An Economic Analysis of Educational Institutions in Late Imperial and Republican China”

“Intergenerational Mobility and Institutional Change in 20th Century China” (with Yuyu Chen and Suresh Naidu)

Both of them are revelant to education, but from differnet angles. The first one focus on the historical sharp change in the education system (the abolishment of the traditional system, 科举制度), and the establishment of modern studies on polyscience in China. He uses the individual level data of employees from the Tianjin- Pukou railway company and checks the difference in wages and departments among people with different educatoin backgrounds. The second one exams the intergenerational mobility regarding the insituitional change during the 1949 (the establishment of the People’s republic of China) to the 1978 (the reform). That is really interesting…

The Jinpu Railway actually passes Jinan, haha! However, it is a shame that the old Jinan railway station was deconstructed in 1992! I have never seen the real building in my life!!! Here is just a photo as a momory.

A few days ago I also read an article related to Chinese people, and it is a doctoral thesis of Xiaohuan Lan:

Permanent Visas and Temporary Jobs: Evidence from Postdoctoral Participation of Foreign PhDs in the U.S. (2009)

The Prevalence of Low-Paid Postdoctoral Positions: The Impact of Foreign PhDs on the Wage of Natives. (2010)

Visa Policies and Research Productivity of Postdocs in the U.S. (2011)

The brief introduction from the  author is available in Chinese on his blog. As you can read from the title, it is about the Green Card and the post-doc market. In the labor market it is always interesting to see the impact of policy changes.

OK…. Overall, it is always nice to enjoy great papers answering interesting questions. Acutally I’m also writing a paper on China now. It is about an innovatoin in the financial system in the ancient China. Hopefully I can get some intersting results! Although most time I care about social network, or theories, it is also great to have the chance to do a research on CHINA! With so many great historical records, I don’t really understand why there are comparably only a few papers…hence, no matter how little my contribution is, I would like a try!

Information, Beliefs and Expectations in Macroeconomics

20 & 21 May 2011

Organized by Kristoffer Nimark (CREI & UPF) and Bartosz Maćkowiak (European Central Bank).

To be honest, I have waited for the conference for a while, as I was writing things on beliefs and expectations. However, this conference is a little bit out of my expectation – so again, my expectations deviates from the truth. My poor background in macro is definitely not enough to support me for understanding the presentations, and among all of them, I picked a few to stay and thus make myself confused. They were:

Exogenous Information, Endogenous Information, and Optimal Monetary Policy
Luigi Paciello | Einaudi Institute for Economics and Finance
*Mirko Wiederholt | Northwestern University
Discussant: Jordi Galí | CREI & Universitat Pompeu Fabra

Learning about Consumption Dynamics
Michael Johannes | Columbia U., Columbia Business School
Lars Lochstoer | Columbia U., Columbia Business School
*Yiqun Mou | Columbia U., Columbia Business School
Discussant: Francisco Barillas | Emory U., Goizueta Business S.

Public’s Inflation Expectations and Monetary Policy
Leonardo Melosi | London Business School
Discussant: Francesco Bianchi | Duke University

Just as I had expected, it was too easy for me to get lost in these presentations. In a few minutes I got the feeling that I don’t know what’s going on so ever. well…Except for the fantastic graphs I have seen, I haven’t gained much intuition from them.

A noteworthy point is in Mou’s presentation, he empirically showed the convergence to rational expectation. I should admit I don’t really understand the techniques he utilized, and so are the debates afterwards. After his presentation, I talked to him with the learning process a little bit, but haven’t benefited a lot… there is still a long way to go.

Also, I found another interesting book to read,

1587, a year of no significance : the Ming dynasty in decline / Ray Huang

Very nice book on history. I really treasure this period of time that I have got enough space to read and think across different subjects. As planned before, I also found Keynes’ book,

A Treatise on probability

Things are so beautiful!

An advantage now is that I have enough time to read and think. Today I found Becker’s book by chance, when I was browsing the literature on “social economics”, or socio-economics. It is quite exciting, and I have realized how deep the water might be- before I was only using my naive intuition that there is something I can contribute soon.

The book I’m talking about now is

Gary S. Becker and Kevin M. Murphy, 2001, Social Economics: Market Behavior in a Social Environment.

Before I was paying more attention solely to network economics, and it turned out to be that they were quite similar to each other in most sense; however, socio-economics is for sure more broad.

Moreover, I took a few hours finishing reading another book,

Salsburg, D. (2002) The Lady Tasting Tea: How Statistics Revolutionized Science in the Twentieth Century

From the name, you can see that this book is about basic statistics. To save time, I read its Chinese translation. Not very long, but very exciting – maybe I have been, and will always be attracted by mathematics and statistics. Especially the later one, perhaps due to the fact that I have so many friends in this area, is one field beyond economics that has influenced me the most, and more on the level of conception and methodology than techniques or actual methods.

@Roma. Things remain to be clear

While reading this book, it reminds me another book I read before, which is about the famous economist Keynes,

Robert Skidelsky, 2005, John Maynard Keynes: 1883-1946: Economist, Philosopher, Statesman

What impressed me most at that time was not Keynes’ contribution to economics – although nobody can neglect that, but his ideas on probability.  Until now, I still have the wish that one day I want to read Keynes’ original book on probability somewhere.

I want to read Becker’s book only for the reason that I need an idea for my history paper. One question I have been seeking for the answer for a while: why do we need to care about the network structure? Before, I was only arguing that the “summation is a naive way to draw the group’s characteristics”; now it seems that I need to really re-think about this argument. In addition to sum or mean, people have developed distribution to help understand the world; furthermore, from central limit theorem, normal distribution can be utilized in most scenarios. Therefore, under what particular case will summation cause a severe problem?

Another thing I’m thinking about now is after reading the “Lady tasting tea”, a term still remains to be explained more clearly: frequency school and Bayesian school’s debate on the definition of probability. On one side we are lucky today that following Baye’s idea will not be regarded as heterodox any more; on the other side, although his idea itself is very simple, how to make a perfect use of it is still a very tricky and should be dealed with carefully.

I’ll stop here for now, and see whether I can gain some new senses soon. This year is too short- I need a longer time to make all things clear.

I have cried for the past four days… actually today I decided not to cry anymore, then met a song, and then tears just fell… I don’t like that, but unfortunately, nothing could have stopped it.

When the sky cried, I realized that there was no need for me to contribute my tears anymore. The city is crying…

Stay firm… and realized that my heart can be touched again by some soft words from a friend. Suddenly I really want to meet him, to see what kind of person he is. Just, curious.

2 months before leaving…not so pretty. How I wish, there is another christmas holiday for us to spend… Just wander in Rome, aimlessly, talk randomly, and pick a gelato as hand whenever we want. That is a kind of luxury now…as I wrote down a few months before,

“would like to go to Roma again, wander around the city aimlessly, touch the leaves and ask them whether I look familiar, and take a seat on the Spanish Steps with a gelato in hand while observing the crowds…”

However…that is only a memory to recall.

@Pompei

Today’s aim: add an export shortcut for the menu File -> Export -> PDF(pdflatex), both keyboard shortcut and a button on the toolbar.

To modify LyX’s toolbar, you need to go to its installation folder and find “stdtoolbars.inc”. Mine is under the default path: “C:\Program Files\LyX20\Resources\ui”. Then please find

Toolbar “view/update” “View/Update”
Item “View” “buffer-view”
Item “Update” “buffer-update”

After this, if you want to keep the Update button, then add this line after it:

Item “Export” “buffer-export pdflatex”

The result is shown like below

Or you can do it like me, just put the Update line into comment, i.e.

Toolbar “view/update” “View/Update”
Item “View” “buffer-view”
#Item “Update” “buffer-update”
Item “Export” “buffer-export pdflatex”

Moreover, if you love keyboard shortcut better than buttons on the toolbar, then please follow a few steps:

1. go to “Tools->Preferences->Editing->shorcuts”
2. under the “function” column, there is “document and window”, then find “buffer-update” and remove it.
3. find “buffer-export-custom”, modify it to “buffer-export pdflatex” and configure the keyboard shortcuts as “ctrl+shift+R”. (If you want to keep the shortcut for update, please choose another keyboard combination as you like)

Now you are able to use the keyboard shortcut for ” File -> Export -> PDF(pdflatex)” as well! Enjoy!

Note: in similar ways, you can modify all the toolbar and shortcut you like!

Actually I began to think about the topic from last Christmas. However, things were not going as well as I expected. A few months later I posted a notice on my chinese blog and was looking for someone to collaborate on this. Unfortunately, not that ideal either.

Now there is only one month left for me to work on it. Moreover, I also noticed that the 4th Chinese R conference is going to take place on the 28th of May. Well, since social network is one topic on the list, I really want to go back and see what’s going on. Ideally, if I can finish the paper by 21th of May, and I can also find a funding for this trip, I would like to go back to China for a few days and give a speech… Well, then time is pretty tight, and I don’t know even where I can ask for money. Does UPF or BGSE have a flyout funding? Any helpful informaion?

Well… a little off topic. This time, we found several great papers to follow. Before, I was only reading Jackson’s book on social and economics networks, so I knew nothing about health. Interestingly, there are more people from sociology who are working on social network. Checked out some demographic journals,  tons of relevant papers appear.

However, although we have got enough idea now and it seems to have a possible way, still there are a lot of questions remained. As I wrote down a year before, my idea is concentrated around “information”. In particular, here I want to try to stress the importance of information on expectation. From the context’s view, when it comes to health, people tend to be either over optimistic or passive,  and as a result, the risk is either overestimated or underestimated. From the common sense, if people do not hold a nearly correct expectation, then for sure, their behaviors  will diverge from the optimal path. This time, I want to find out the way to model this process, and further, check the validity of the model by some empirical methods.

Maybe now, most challenges lie in the concern of time. Somehow luckily, I only have two courses to take this semester, which ensures more free time for me to work on a project. But still, I don’t know how much I can finish. Things are going more and more stressful.

Among all issues related to (public) health, this time we may pick some epidemics, and a good choice should be HIV/AIDS. HIV has become such a hot topic in recent years, and as a sexual disease, it does have a lose link to social network, or specifically, sexual network, including the homosexual and heterosexual ones. Moreover, the risk perceptions of HIV/AIDS will also influence or even determine corresponding sexual behaviors – that’s may be a reason why there are so many public targeted education in countries all around the world.

Hopefully I was not too optimistic this time (otherwise for me, I cannot follow the optimal path as well ^_^), and also, not too ambitious. Learning by doing, that’s how we will benefit from this project.