Monday, February 22, 2016

There is a new paper coming out: "Discrimination in the laboratory: A meta-analysis of economics experiments," by Tom Lane in the European Economic Review.


The abstract reads:

"Economists are increasingly using experiments to study and measure discrimination between groups. In a meta-analysis containing 441 results from 77 studies, we find groups significantly discriminate against each other in roughly a third of cases. Discrimination varies depending upon the type of group identity being studied: it is stronger when identity is artificially induced in the laboratory than when the subject pool is divided by ethnicity or nationality, and higher still when participants are split into socially or geographically distinct groups. In gender discrimination experiments, there is significant favouritism towards the opposite gender. There is evidence for both taste-based and statistical discrimination; tastes drive the general pattern of discrimination against out-groups, but statistical beliefs are found to affect discrimination in specific instances. Relative to all other decision-making contexts, discrimination is much stronger when participants are asked to allocate payoffs between passive in-group and out-group members. Students and non-students appear to discriminate equally. We discuss possible interpretations and implications of our findings."

Thanks Christine Exley who pointed this paper out to me.

Wednesday, February 17, 2016

Overrated Men

Josh Logue writes at insidehighereducation, about "Overrated Men Do the biology students celebrated (perhaps undeservingly) for their intellect always seem to be male? A new study says the answer lies in gender bias." on February 12, 2016

"Male students appear to consistently and significantly overrate the abilities of other male students, whereas female students showed no such bias, according to a new study in the journalPLoS ONE."

"Researchers at the University of Washington surveyed more than 1,700 students in three introductory biology classes, asking them to nominate those who they felt were doing exceptionally well in the class. Even after controlling for outspokenness and actual graded performance, male students in each of the classes consistently overestimated the performance of other men to the tune of an assumed 0.765 bump in grade point average. Effectively, for an outspoken female student to be nominated at the same rate as an outspoken man, her class GPA would need to be three quarters of a point higher than that of the guys.
Female students, on the other hand, demonstrated no statistically significant bias. Researchers found they were equally likely to nominate male and female students with equivalent GPAs."

The paper is called " Males Under-Estimate Academic Performance of Their Female Peers in Undergraduate Biology Classrooms", by Daniel Z. Grunspan  , Sarah L. Eddy , Sara E. Brownell, Benjamin L. Wiggins, Alison J. Crowe, Steven M. Goodreau
Published: February 10, 2016

Here is the abstract:

"Women who start college in one of the natural or physical sciences leave in greater proportions than their male peers. The reasons for this difference are complex, and one possible contributing factor is the social environment women experience in the classroom. Using social network analysis, we explore how gender influences the confidence that college-level biology students have in each other’s mastery of biology. Results reveal that males are more likely than females to be named by peers as being knowledgeable about the course content. This effect increases as the term progresses, and persists even after controlling for class performance and outspokenness. The bias in nominations is specifically due to males over-nominating their male peers relative to their performance. The over-nomination of male peers is commensurate with an overestimation of male grades by 0.57 points on a 4 point grade scale, indicating a strong male bias among males when assessing their classmates. Females, in contrast, nominated equitably based on student performance rather than gender, suggesting they lacked gender biases in filling out these surveys. These trends persist across eleven surveys taken in three different iterations of the same Biology course. In every class, the most renowned students are always male. This favoring of males by peers could influence student self-confidence, and thus persistence in this STEM discipline."

Tuesday, February 16, 2016

Financial Incentives to Increase Physical Activity Among Overweight and Obese Adults

"Framing Financial Incentives to Increase Physical Activity Among Overweight and Obese Adults: A Randomized, Controlled Trial" published online, Annals of Internal Medicine
Mitesh S. Patel, MD, MBA, MS; David A. Asch MD, MBA; Roy Rosin, MBA; Dylan S. Small, PhD; Scarlett L. Bellamy, ScD; Jack Heuer, EdD; Susan Sproat, MS; Chris Hyson, MEd; Nancy Haff, MD; Samantha M. Lee, MD; Lisa Wesby, MS; Karen Hoffer, BS; David Shuttleworth, MS; Devon H. Taylor, BS; Victoria Hilbert, MPH, RD; Jingsan Zhu, MBA, MS; Lin Yang, MS; Xingmei Wang, MS; and Kevin G. Volpp, MD, PhD

Here is the abstract - or what counts as abstract in medical journals:

"Background: Financial incentive designs to increase physical activity have not been well-examined.

Objective: To test the effectiveness of 3 methods to frame financial incentives to increase physical activity among overweight and obese adults.

Design: Randomized, controlled trial. (ClinicalTrials.gov: NCT 02030119)

Setting: University of Pennsylvania.

Participants: 281 adult employees (body mass index ≥27 kg/m2).

Intervention: 13-week intervention. Participants had a goal of 7000 steps per day and were randomly assigned to a control group with daily feedback or 1 of 3 financial incentive programs with daily feedback: a gain incentive ($1.40 given each day the goal was achieved), lottery incentive (daily eligibility [expected value approximately $1.40] if goal was achieved), or loss incentive ($42 allocated monthly upfront and $1.40 removed each day the goal was not achieved). Participants were followed for another 13 weeks with daily performance feedback but no incentives.

Measurements: Primary outcome was the mean proportion of participant-days that the 7000-step goal was achieved during intervention. Secondary outcomes included mean proportion of participant-days achieving the goal during follow-up and mean daily steps during intervention and follow-up.

Results: The mean proportion of participant-days achieving the goal was 0.30 (95% CI, 0.22 to 0.37) in the control group, 0.35 (CI, 0.28 to 0.42) in the gain-incentive group, 0.36 (CI, 0.29 to 0.43) in the lottery-incentive group, and 0.45 (CI, 0.38 to 0.52) in the loss-incentive group. In adjusted analyses, only the loss-incentive group had a significantly greater mean proportion of participant-days achieving the goal than control (adjusted difference, 0.16 [CI, 0.06 to 0.26]; P = 0.001), but the adjusted difference in mean daily steps was not significant (861 [CI, 24 to 1746]; P = 0.056). During follow-up, daily steps decreased for all incentive groups and were not different from control.

Limitation: Single employer.

Conclusion: Financial incentives framed as a loss were most effective for achieving physical activity goals.

Primary Funding Source: National Institute on Aging."

Here is a write up by medpage today.

"There's plenty of previous research on the behavioral economics concept of loss aversion, or people's tendency to prefer avoiding losses to getting gains. In an interview with MedPage Today, co-author Mitesh Patel, MD, MBA, also at UPenn, said that the results were in line with what they were expecting.
But he added that this study was the first to test the loss aversion principle in a prospective study of employees with physical activity as an outcome."

Here is a figure from a write up by UPenn


Friday, February 12, 2016

Wanted in China: More Male Teachers, to Make Boys Men

A NYtimes article "Wanted in China: More Male Teachers, to Make Boys Men
By JAVIER C. HERNÁNDEZFEB. 6, 2016"

starts like that:

"FUZHOU, China — The history class began with a lesson on being manly.

Lin Wei, 27, one of a handful of male sixth-grade teachers at a primary school here, has made a habit of telling stories about warlords who threw witches into rivers and soldiers who outsmarted Japanese troops. “Men have special duties,” he said. “They have to be brave, protect women and take responsibility for wrongdoing.”

Worried that a shortage of male teachers has produced a generation of timid, self-centered and effeminate boys, Chinese educators are working to reinforce traditional gender roles and values in the classroom.

and then there is

"Zhou Jiahao, 18, a senior at the school, said he did not think China faced a masculinity crisis in its classrooms. But he said boys felt more confident when they took classes together. The school offers courses in etiquette, coding and wilderness survival, among others.

“In classes with female students, we might not dare speak out,” he said. “When it’s just boys, we feel much freer.”"

This of course is not exactly what we seem to see in studies in US colleges, see my older blogpost on Women don't speak up! here

Thanks to David Yang

Wednesday, February 10, 2016

Immigrants and Gender Roles: Assimilation vs. Culture

Les Picker at the NBER digest writes about a paper by Francine D. Blau

"Immigrants and Gender Roles: Assimilation vs. Culture"

The abstract reads:

"This paper examines evidence on the role of assimilation versus source country culture in influencing immigrant women’s behavior in the United States—looking both over time with immigrants’ residence in the United States and across immigrant generations. It focuses particularly on labor supply but, for the second generation, also examines fertility and education. We find considerable evidence that immigrant source country gender roles influence immigrant and second generation women’s behavior in the United States. This conclusion is robust to various efforts to rule out the effect of other unobservables and to distinguish the effect of culture from that of social capital. These results support a growing literature that suggests that culture matters for economic behavior. At the same time, the results suggest considerable evidence of assimilation of immigrants. Immigrant women narrow the labor supply gap with native-born women with time in the United States, and, while our results suggest an important role for intergenerational transmission, they also indicate considerable convergence of immigrants to native levels of schooling, fertility, and labor supply across generations."

Les Picker writes about that paper:
"Source country gender roles influence immigrants' behavior in the United States, even among second-generation women, but assimilation also occurs.

Immigrants are an increasing presence in the United States. The share of the foreign-born in the population grew from 4.8 percent in 1970 to 12.9 percent in 2012, and the share of U.S. children who were immigrants themselves or who had at least one immigrant parent increased from 13 percent in 1990 to 23 percent in 2008.

Along with the rise in immigrant population has come a shift in the predominant origins of immigrants. The principal source of immigrants has shifted from countries in Europe, with cultures that are broadly similar to that of the United States, to regions with very different cultures and traditions. How much does an immigrant's source country affect their adjustment to American life? What role does assimilation play in that adjustment? Do differences between immigrants and natives in labor supply, education, and fertility carry over to the second generation, or do second generation women fully assimilate to native patterns?

In Immigrants and Gender Roles: Assimilation vs. Culture (NBER Working Paper No. 21756), Francine D. Blau reports on a research program with Lawrence M. Kahn that examines the roles of assimilation and source country culture as influences on immigrant women's behavior. The research focuses in particular on labor supply because immigrants increasingly come from countries that have a more gender-based division of labor than is currently the case in the United States. Typically, the source countries have lower female labor force participation rates and higher fertility rates than the United States. There has been a growing gap between the labor supply of native and immigrant women in the U.S. since 1980.

The researchers find considerable evidence that source country gender roles influence immigrants' behavior. This influence appears to extend to second-generation women. At the same time, they also find evidence of assimilation. Immigrant women narrow the labor supply gap with native-born women as they spend more time in the United States. There is also considerable convergence of immigrants to native levels of schooling, fertility, and labor supply across generations. For second-generation women, fertility and labor supply in their mother's source country have a larger association with their behavior than the corresponding practices in their father's source country.

Blau points out that in the future, immigrant source countries may become more similar to the United States, thus reducing the effect of source country gender roles on the behavior of first- and second-generation immigrant women. This has already begun to happen with respect to fertility. The fertility of immigrant women relative to natives has been falling rapidly in the most recent immigrant cohorts."




Tuesday, February 9, 2016

How Economists Would Fix Online Dating

My work with Soo Lee on roses was mentioned in a Wall Street Journal article By CHRISTOPHER MIMS on Feb. 8, 2016

How Economists Would Fix Online Dating
A ‘thick’ market and cost-benefit analysis help avoid ‘romantic unemployment’

"One recent experiment in improving online dating sites through signaling mechanisms, conducted by economists Soohyung Lee and Muriel Niederle, gave members of a Korean dating site a limited number of virtual roses, meant to indicate special interest in a person, to include with their messages to potential matches. The result was that people were more likely to respond to those who sent them a rose..."

I think here is a version open to everyone

Monday, February 8, 2016

Competitiveness and Wages of MBA's

This is a paper I always wanted to write:

Reuben, E., P. Sapienza, and L. Zingales: "Taste for competition and the gender gap among young business professionals,"

There are two reasons I find this work interesting: First, it related to a literature that helps understand what psychological traits are linked to labor market outcomes. Second, it shows the external relevance of competitiveness: see also my paper with Thomas Buser and Hessel Oosterbeek:  Gender, Competitiveness and Career Choices,” Quarterly Journal of Economics, August 2014, 129 (3): 1409-1447, and see also my former blogposts  here and here)

The abstract reads:

"Using an incentivized measure of individuals’ taste for competition, this paper investigates whether this taste explains subsequent gender differences in earnings and industry choice in a sample of high ability MBA graduates. We find that “competitive” individuals earn 9% more than their less competitive counterparts do. Moreover, gender differences in taste for competition explain around 10% of the overall gender gap. We also find that competitive individuals are more likely to work in high-paying industries nine years later, which suggests that the relation between taste for competition and earnings persists in the long run. Lastly, we find that the effect of taste for competition emerges over time when MBAs and firms interact with each other."

Their main results can be seen in the following figures and tables:
First even among MBA's it seems there is a gender gap in tournament entry.


While risk aversion and confidence can account for some of that gender gap in tournament entry, a substantial gender gap remains.



Second, male MBA's have a higher salary after graduation than female MBA's.


Now, to assess the external relevance of competitiveness:


Competitiveness is highly positively correlated with higher earnings.


Finally, competitiveness remains an important variable even controlling for gender, and can account for about 10% of the gender gap in earnings.

They write:
"How important is the role of taste for competition in accounting for the gender gap in earnings? One way to answer this question is to compare the impact of taste for competition on the gender coefficient to the impact of other control variables on the same coefficient. This can be done by looking at column III, which includes all the variables in Table 1 except for the choice of tournament. Including these control variables noticeability reduces the gender gap by 20.7% (the gender coefficient changes from–0.122 to –0.097). This result puts the effect of taste for competition in perspective. Namely, the single experimental measure of taste for competition explains around half as much of the gender gap in earnings as a rich set of variables that include demographic characteristics, academic performance, and experimental and survey measures of important psychological attributes."

Finally, they have a great section to address to what extent competitiveness is really distinct from risk aversion: They write the following:

"Taste for competition and the choice of tournament

A clever feature of the experimental design of Niederle and Vesterlund (2007) is that participants make two choices between tournament and piece-rate. In one case, participants perform under the chosen payment scheme while in the other case the payment scheme is simply applied to their past performance (see section 3.1). We will refer to the choice of the tournament in the latter case as “uncompetitive tournament choice.” Because it does not include performing in a competitive environment, Niederle and Vesterlund (2007) argue that the choice between piece-rate and uncompetitive tournament is unaffected by the participants’ attitudes towards competition. If this is the case and the association between earnings and choosing the tournament is driven by taste for competition, then we should observe a weaker relation between earnings and uncompetitive tournament.

To evaluate whether choosing uncompetitive tournament is associated with earnings, we run regressions like the ones reported in columns II and IV of Table 3. In some regressions, we simply substitute tournament with uncompetitive tournament. We find that the coefficients for uncompetitive tournament are positive, but they are not statistically significant and they are half as large as the comparable coefficient in Table 3. In addition, the change in the gender coefficient due to the inclusion of uncompetitive tournament is much smaller and is not statistically significant. In other regressions, we include both tournament and uncompetitive tournament. We find that the coefficient for tournament is both economically and statistically significant whereas the coefficient for uncompetitive tournament is close to zero and far from statistical significance. These results provide compelling evidence that the association between tournament and earnings is indeed driven by the participants’ attitudes towards competition and is not related to the choice of a tournament per se."