What I learned from teaching PhD-level “tool set” classes

This summer I had the pleasure to teach two PhD level modules: Introduction to R and Programming and Project Management. Both of these classes are designed to equip rising second-year PhD students with the necessary programming skills needed for independent research.

I also participated in the Teaching in Triangles program as part of my effort towards earning a Certificate of College Teaching. This program consists of pair-wise peer observations (with other PhD students who are teaching summer classes), and we get extensive feedback on the content and style of our teaching. Here are the two main lessons for me:

  • It is challenging to achieve a balance between pure lecturing and student discussions, especially in software classes. I designed the classes to contain short, in-class assignments that allow students to check their understanding right after a new concept/procedure is introduced. But when I explain the recommended solutions, I tend to lecture on and on without leaving much time for students to ask questions.
  • Students are more engaged when they feel they can contribute to the class. In the last class when I talked about programming and project management in collaborative projects, I asked students to brainstorm the good practices in this setting and emphasized that they would need to share their insights with the rest of the class. My students were super engaged and raised good points that complemented my lecture.

My experience as an instructor also makes me realize how much effort goes into course preparation. Bravos to the good teachers I encountered throughout the years! Hopefully I will become a better teacher over time.


Philip Oreopoulos on behavioral economics for education

Professor Philip Oreopoulos from the University of Toronto is our ERID visitor this week. Today he gave a talk on applications of behavioral economics in economics of education.

Individual rationality is one of the fundamental assumptions widely held in traditional economic theory. This assumption allows economists to place model decision-making process as an optimization process given a well-defined objective under a set of constraints.

But when individuals don’t think rationally, many modeling frameworks need to be revised. Professor Oreopoulos specifically mentioned the dual process theory in psychology and how that justifies the present bias. Interested readers can refer to this book by Daniel Kahneman.

A few signs of system I show up in the behavior of students while they learn. They tend to focus too much on the present, sometimes sacrificing long-term benefits in favor of temporary pleasure. They rely too much on routine. They focus too much on negative identities. It is worth noting that social identity can exacerbate present bias by perpetuating irresponsible lifestyles through social networks.

The speaker provided some evidence that education could change preferences. Studying requires efforts, but the payoffs are only realized gradually over the life course. Therefore, to get an education students need to overcome their tendency to “enjoy the present” without considering long-term consequences of bad time management.

Behavioral economics is increasingly used to analyze education policies. One important topic is how much does the availability of college admissions information help disadvantaged students depending on whether they actively seek the information. Individual aspiration and family resources play vital roles in determining the overall impact of increasing availability and transparency of the information on college choices.

One of my favorite pieces of research on this topic is done by Caroline Hoxby and Sarah Turner. They mail packages containing personalized information to disadvantaged students on college admissions statistics and scholarship availability, thereby increasing their awareness of the affordability of selective colleges. As a result, the number of applications to more selective colleges increased and so does matriculation in those colleges. This suggests that simple, inexpensive information interventions can make a big difference in the decision-making process of disadvantaged individuals.

The fun of delving into household surveys

In the week of the semester I was chatting with another grad student in our department. And he was curious about my research project.

“So what are you gonna do for your independent study?”
“Well, I plan to use some Chinese household survey data to analyze the consequences of China’s internal migration on the left behind children.”
“Sounds interesting! But where do you get the data?”
“I got the data from UNC. It’s a longitudinal data set and contains a lot of information that will be useful for my analysis. But I still need some time to clean it and make sure it’s up to the task.”
“Yeah… You can never predict what you can get from these data. That’s why I chose to write a theoretical paper.”

I have had similar conversations with other friends. While I agree that dealing with large-scale household surveys can be frustrating, I don’t think we should shy away from them for this reason. Household surveys provide rich information on the structure and operations of the families. By looking at real world household level data, you get a better sense of how households make decisions (both as a whole and as separate individuals bargaining with each other). You also become more aware of the reasons why some variables can never be measured and why some values are always missing. This is extremely evident in time-use data. Response rates for “yes or no” questions are much higher than questions that asks for a specific number of hours spent on a particular activities. This is hardly surprising given the difficulty of keeping track of time use. Even if we have statistics about how much time mothers spent caring for their children, these are subject to severe measurement errors.

I am using China Health and Nutrition Survey, which contains a variety of questions about household structure, employment decisions, time use, and health and nutrition. It’s been widely used in public health research, but economists can answer interesting questions based from this as well (here and here).

Shelly Lundberg on Educational Inequality and Returns to Skills

DuPRI‘s seminar series in the fall started with a fascinating talk by Shelly Lundberg (UCSB) on her recent research on differential returns to skills in different environments. Abstract is below:

I examine the effects of cognitive ability and personal traits on college graduation in a recent cohort of young Americans, and how the returns to these traits vary by family background, and find very substantial differences across family background groups in the personality traits that predict successful completion of college, particularly for men. The implications are two-fold. First, the returns to non-cognitive traits may be highly context-dependent. Second, policy discussion concerning educational inequality should include, not just the possibilities for re-mediating the skill levels of poor children, but also approaches to changing the environments that limit their opportunities.

Inequality in education in the US is widely documented and extensively researched. Policy interventions have often focused on helping children from disadvantaged backgrounds to develop skills which will supposedly help them succeed, but the effect of family background is largely viewed as a secondary source of educational inequality.

The skills of children are often measured through reports of behavior by teachers or parents. These often include internalizing vs. externalizing behaviors, antisocial behaviors, and tendency towards violence (e.g. fighting with classmates). While this is convenient, using behaviors as proxies for skills is problematic. Children’s behaviors, like adults’, are determined not only by their personal traits but also by the environment and constraints they are faced with.

Lundberg used the widely cited NLSY data in the US. NLSY data contain measurement of the “Big 5” personality inventory which are acknowledged metrics for personality in psychology. The five dimensions of personality traits are openness to experience, conscientiousness, extroversion, agreeableness, and neurotic-ism (emotional stability). Lundberg took the measures of personal traits for people from different backgrounds and estimated the correlation between these traits and educational attainment (defined as graduation from college, and broader educational achievement). She divided the sample into four groups according to two criteria: 1) mother’s education (some college and above vs. no college), and 2) whether the child was living with BOTH BIOLOGICAL parents at the first wave of the survey. These categorization breaks the sample down into four groups, with people having highly educated mothers and living with both biological parents being the most advantaged one.

A simple model about children’s educational outcome was presented. Children’s educational achievement is a function of focus and information. Focus is the personal efforts and information is the resources available. Her argument was that children in more advantaged households have more resourceful parents who will make their “focus” more rewarding. Parental resources are also assumed to be a perfect substitute for the information children can get at school. This assumption can be challenged if parents with higher social-economic status (SES) can improve the quality of the information.

Her findings suggest that people from more advantaged families receive a higher return (in terms of education) on conscientiousness, while people from disadvantaged backgrounds receive a higher return on openness. These patterns are the same regardless of gender, though the effects appear to be more distinct for men. There are racial differences as well — black men seems to receive a higher return on their openness.

It is not surprising that family background affects the returns to your skills. Being born in a rich and educated family gives a person access to good education, nice living environment, less obligation to shoulder family responsibilities (though this might not be a good thing) and more opportunities to explore personal interests. The resources of the parents have an instrumental impact on how children perceive which skills will be useful. Expectations of the parents also matter. If parents see the education of their children as an investment, they would invest more in promising children, thus making the returns to “focus” higher for more gifted children. Peer effects (spillover) matter as well. The level of openness should matter more for someone who grow up in a poor neighborhood where a role model is nonexistent — he might assume this is the way it is and never dare to push himself nearer to success.

Although the topic is tremendously interesting, there is a caveat. These results cannot be interpreted as causality because personality may well be endogenous. Although personality seems to be stable during an individual’s lifespan, there is no definitive evidence that life-cycle events cannot change one’s personality. Moreover, some personal traits (e.g. openness) might interact with educational attainment and evolve. For instance, being in college might make an introverted person more open to new ideas and more adaptable to new cultures, which in turn increases his earning potentials.

What can education bring you?

I discovered this wonderful website Why Poverty.  It contains a series of poverty independent documentaries on poverty-related topics. Among them, “Education, Education” by Weijun Chen (director of Please Vote for Me) focuses on private colleges in China. Highly recommended to anyone who wants to know more about post-secondary education in China. Here’s the abstract.

How do you choose a college when you’re the first person in your family who can read? Or pay for it when 4 years of schooling costs sixty years of income? What is it like to join the “ant-tribe”, the 2 million newly graduated Chinese who, every year, can’t find work?  And what if the only job you could find involved selling education to other students, even if you knew it was worthless?
Tell us what you think. Nelson Mandela once said “Education is the most powerful weapon which you can use to change the world” but is its value undermined when, like in China, it becomes a commodity?

You can tell an information asymmetry story. Rural students are not as well-connected and informed as their urban peers. Most of them, when faced with college entrance decisions, simply went through the list of schools and picked whichever sounds nice. Private colleges can easily win the trust of parents through carefully designed propaganda. The high value of college degrees and the low probability of getting admitted to top universities drives a wedge between supply and demand of higher education. Without an underdeveloped market for professional colleges, private colleges (enterprises in nature) emerge as a seemingly good alternative. These private colleges extract money from uninformed students without teaching them useful skills.

The number of private colleges has increased 30 times in the last decade. Each year over 2 million graduates do not find jobs.

Just as printing more money makes money valueless, the increasing number of college graduates intensifies their competition for jobs. People are getting more education at higher ranked institutions, most often only to signal. Universities are categorized into several levels. Students from lower levels often have to get a master’s degree from a higher ranked university to increase their bargaining power in the job market. And those graduates from no-name private colleges will soon discover painfully that their degree is just a piece of worthless paper.

I would love to explore this topic more in the future.

A flavor of democracy

What is democracy? Many of us might struggle to come up with an answer. The documentary Please Vote for Me depicts a democratic voting process in a third grade class at Evergreen Primary School in Wuhan, China. Will a group of third graders know how to vote? Well, I started watching the movie with this doubt, and it fades away as the story unfolds. Afterall, voting in primary school classroom is really not that different from one in the adult world.please-vote-for-me-poster

As the teacher emphasized, this election of class monitor is designed to be democratic. Ironically, the first (implicit) round of the election seems to contradict this claim: three candidates for class monitor were chosen by the head teacher. Note: they are not nominated by the students. How the head teacher came up with these candidates is the single biggest secret in this election, although one can make an educated guess by observing the profession of their parents. The incumbent, Lei, was confident boy and always anxious to maintain the order of the class. He had been the class monitor for the past two years. Lei was faced with two challengers — Cheng, a chubby boy who was very good at public speaking, and Xiaofei, an introverted girl struggling to establish her self-confidence.

Not surprisingly, the game between the three candidates turned into a competition of maneuvers between their parents. Cheng’s parents taught him to play nice in front of his opponents while spreading rumors and creating chaos when necessary. He also fully utilized his outstanding public speaking skills, winning cheers and applause during his speech. By contrast, Lei adopted a “hands off” approach at first. “I’ll let my classmates make their own choice.” he said to his parents. But after he found out rumors were dissolving his power base, he felt the urge to make up for it. He invited all his classmates to take the monorail, which was a luxury in Wuhan then (I can testify as a native of Wuhan). Lei quickly won the support of many classmates by this sincere move.

The debating section was probably the most hilarious part of the movie. Somehow it reminds me of the American presidential debate. Well, of course you can argue the latter contains more sophistication and is (seemingly) more civilized. I remember Cheng criticizing Xiaofei:  “you eat too slow”. My reaction was: “What? As girls we are supposed to eat slow!”

The movie made me think about what I went through as a candidate internal vice chairperson of my undergraduate university choir. We twelve people, the newly proposed executive committee, went through a two-day overnight campaign to prove that we were capable of the job. Choir members and past executive committee members relentlessly asked us about our year plan (literally every detail of every single function) and our budget. This campaign was definitely a challenging and unforgettable experience. Two lessions were learnt: 1) You can never convince others if you doesn’t know your arguments perfectly well, and 2) you only need the majority of voters to win an election.

While the movie seems to focus on behaviors of the candidates, it records reactions from other students as well. I wonder what thought process the other students (the voters) went through to choose their future monitor. For the past two years they had been assigned one and they seemed to be doing just fine. When you place the “sacred vote” in their hands, will they hold onto it or disregard it? Will they know the importance of them — the voters — as independent entities affecting the distribution of power in the future? These are open ended questions for educators to reflect upon.

This movie is available on NetFlix. Thanks to Marc for recommending.

Parent expectation and early child investment

Flavio Cunha from University of Pennsylvania is our ERID visitor this week. He gave an enlightening talk yesterday on preferences, beliefs, and early investment in children. His talk reminds me of a recent New York Times article on the same topic.

Child psychologists have found a positive relationship between how much time parents spend with children and children’s cognitive skills. The gap in cognitive ability between children from rich and poor families appears at birth and continues widening up into their adulthood. Strikingly, 80% of the gap is formed before the age of five. It seems that high income parents tend to invest in their children long before the children are born, while poor parents may have let many precious opportunities slip by without noticing them. If parents of lower social and economic status simply don’t know that spending time with their children and offering encouragement are rewarding practices, policy makers can potentially tell them this and let them make more effective investments.

Professor Cunha introduced an interesting concept called “reference point”. It means the parents’ expectation of the child’s cognitive development process. For example, a parent may expect her child to be able to construct a full sentences by the first birthday. Reference points shape the investment patterns of parents. Investment in children is like learning. Parents learn how capable their children are by observing their accomplishments and comparing these with their reference points. They then adjust their investment strategies accordingly. For example, parents of a child who speaks relatively late may invest more into the child to prevent the child from lagging behind even further. However, the reverse could happen: Children who do not meet parents’ expectations may discourage parents from investing more into education. Professor Cunha hypothesized that parents will be more responsive in investment if their children are below the reference point.

Another related concept is parents’ beliefs about returns to their investment. Professor Cunha hypothesizes that there is only one true return, but parents have different beliefs about the distribution of this return. Beliefs are also subject to changes because of learning.

Professor Cunha surveyed a subsample of first-time pregnant women from the CPS sample. Most of them are single mothers, have high school diploma or lower education, and are unemployed. Although he didn’t go to details regarding his survey, he offered two pieces of advice from his experience:

1) Design your survey to be comprehensible for your targeted respondents. The majority of his sample are not educated and had a difficult time thinking about probabilities, so he asked them to give a range of a child’s expected accomplishments. For example, he asked these women when they think should be the earliest possible and latest possible age that a child could speak a full sentence.

2) Based on the characteristics of your sample, some questions may not generate enough variation as you would like to. Because the women surveyed in his sample come from low-income families, they would almost surely answer “yes” to the question “have you ever been a babysitter before?” Therefore this question tells little about how much child-care knowledge a woman is compared with others in the same sample.

As I was listening to this talk, I thought about the Chinese Household Income Project 2002 wave I’ve been analyzing in the past few months. There is a question “what level of education do you expect your child to accomplish?” Over 80% of rural parents expect their children to go to college. Children with more aspiring parents perform better overall. But it may well be that parents learn how capable their children are by their performances and adjust their expectations accordingly.