608 research outputs found
A new insight into the gender gap in math
No full textIn the Early Childhood Longitudinal Study Kindergarten Cohort, I find that the gender gap is not uniform across the distribution of math skills and that these quantile-specific gaps vary with age. Specifically, girls at the top of the distribution initially fall behind boys but manage to catch up later. At the same time, girls in the lower parts of the distribution lose ground. In fifth grade, a gender gap of 0.2 standard deviation, about 2.5 months of schooling, is observed across the entire distribution. Overall, these patterns indicate the possibility that low performing girls become worse and vice versa. These results demonstrate important dynamics of the gap that are relevant for policy, but that the mean gap fails to show. © 2010 The Author. Bulletin of Economic Research © 2010 Blackwell Publishing Ltd and the Board of Trustees of the Bulletin of Economic Research
The trend in suicide methods in South Korea in 1997–2015
No full text© 2017 Taylor & Francis. South Korea exhibited the highest crude suicide rate in the world. To better understand this phenomenon, the author analyzed all suicides in South Korea from 1997 to 2015 and charted the trend in suicide methods by gender. Over time, both genders rapidly chose hanging for suicide at the expense of drug/pesticide poisoning. Gassing was hardly used in the beginning, but its recent gain in use is noteworthy. Including undetermined deaths did not change the main results. The author regressed hanging on demographics and found that hanging was particularly chosen by ever-married men of prime working age with a respectable level of education
Bayesian probabilistic damage detection of a reinforced-concrete bridge column
No full textA Bayesian probabilistic approach for damage detection has been proposed for the continuous monitoring of civil structures (Sohn H, Law KH. Bayesian probabilistic approach for structure damage detection. Earthquake Engineering and Structural Dynamics 1997; 26: 1259-1281). This paper describes the application of the Bayesian approach to predict the location of plastic hinge deformation using the experimental data obtained from the vibration tests of a reinforced-concrete bridge column. The column was statically pushed incrementally with lateral displacements until a plastic hinge is fully formed at the bottom portion of the column. Vibration tests were performed at different damage stages. The proposed damage detection method was able to locate the damaged region using a simplified analytical model and the modal parameters estimated from the vibration tests, although (1) only the first bending and first torsional modes were estimated from the experimental test data, (2) the locations where the accelerations were measured did not coincide with the degrees of freedom of the analytical model, and (3) there existed discrepancies between the undamaged test structure and the analytical model. The Bayesian framework was able to systematically update the damage probabilities when new test data became available. Better diagnosis was obtained by employing multiple data sets than just by using each test data set separately. Copyright (C) 2000 John Wiley & Sons, Ltd.The "rst author wishes to express his sincere thanks to Professor Gerard C. Pardoen and his students at the
University of California at Irvine for providing an opportunity to observe the bridge column test. Also, the
authors are indebted to Dr Charles R. Farrar and Dr Scott W. Doebling of the Los Alamos National
Laboratory for providing the vibration test data. This research was partially sponsored by the National
Science Foundation under Grant No. CMS-95261-2
The influence of birth season on mortality in the United States
No full text© 2016 Wiley Periodicals, Inc.Objectives: Birth season is related to a variety of later outcomes. Among them, mortality is of great interest because it represents lifetime health outcomes. We examined the relationship between birth season and mortality in the US. Methods: We merged the US National Health Interview Survey (NHIS) and NHIS public-use linked mortality files and analyzed 17,082 men and 19,075 women who were followed for 20 years from 1986 to 2006. We used the Cox proportional hazards model to relate birth quarter to mortality, controlling for birth year fixed effects. Results: After controlling for years of schooling and birth year fixed effects, we found that, relative to men born in the first quarter, men born in the fourth quarter were 11% less likely to die. For women, the benefit was the largest for women born in the third quarter who were 14% less likely to die than women born in the first quarter. In the relationship between birth season and mortality, cardiovascular diseases played a noticeable role for men and malignant neoplasms for women. Conclusions: These results were consistent with those for some developed countries, but not entirely with those for contemporary developing countries and developed countries of the past. Simple mechanisms based on the perinatal environment cannot account for the inconsistent results. We suggest that family background may play some, but not an exhaustive, role in the relationship between birth season and mortality. Am. J. Hum. Biol. 28:662–670, 2016. © 2016 Wiley Periodicals, Inc
Disappearing seasonality in birthweight
No full text© 2016 Wiley Periodicals, Inc.Objectives: We estimated seasonality in birthweight over time and assessed how seasonality changed. Methods: We analyzed all full-term singletons (N = 8,268,693) born in South Korea in 1997–2014. We first pooled all years and regressed birthweight on birth season while flexibly controlling for a large set of covariates. We then repeated the analysis by birth year and charted the trends in seasonality in birthweight. Results: When we pooled all years, babies born in winter were the heaviest, while those born in summer the lightest; the difference in birthweight was about 11 g. When we analyzed the data by birth year, however, seasonality almost disappeared by the end of the period. Conclusions: Whatever causes the seasonality has lost its influence in Korea. Replication studies can determine whether other countries exhibit the same patterns. Am. J. Hum. Biol. 28:767–773, 2016. © 2016Wiley Periodicals, Inc
Is leg length a biomarker of early life conditions? Evidence from a historically short population
No full text© 2015 Wiley Periodicals, Inc.Objectives: While one group (Positive Group) has argued that leg length is a more accurate biomarker of early life conditions than height, another group (Negative Group) has challenged this argument. Analyzing Indonesian data, we attempt to reconcile these contrasting arguments. Methods: The sample consists of 4,193 men and 4,684 women, aged 40-70. We regress leg length, trunk length, and height each on education (a proxy for early life conditions), age, and ethnicity. We also adjust for hip size and shrinkage. Results: The relationship is statistically significant for leg length, which is generally consistent with the assertion of the Positive Group. However, the relationship is smaller than that for height, which is generally consistent with that of the Negative Group. Specifically, an additional year of schooling is associated with a 0.080 cm longer leg length for men and 0.078 cm for women. The corresponding figures for height are 0.260 cm and 0.201 cm. This remains true when the magnitude of the relationship is compared with the mean length. Conclusions: Small sample sizes appear to drive the Negative Group's finding that leg length is not statistically significantly related to early life conditions. However, the magnitude of the relationship confirms the Negative Group's argument that leg length is not a more accurate biomarker of early life conditions than height
The dynamics of the evolution of the Black-White test score gap
No full textWe apply a quantile version of the Oaxaca-Blinder decomposition to estimate the counterfactual distribution of the test scores of Black students. In the Early Childhood Longitudinal Study, Kindergarten Class of 1998-1999 (ECLS-K), we find that the gap initially appears only at the top of the distribution of test scores. As children age, however, the gap at the top shrinks whereas the gap in the middle part of the distribution grows. Moreover, the gap due to differences in the effect, rather than amount, of characteristics becomes important. © 2012 Copyright Taylor and Francis Group, LLC
How does the ordering of questions affect elicited time preferences?
No full textSince time preferences constitute a concept fundamental to economics, many economists have attempted to elicit time preferences by using multiple price lists. In such endeavours, however, little attention has been paid to the effect of the ordering of questions on elicited time preferences although the ordering effect is well known. We analysed a representative sample of the Indonesian population (13,870 men and 15,858 women) by applying censored maximum likelihood regressions. We exploited the randomized ordering of two series of delay questions (1- and 5-year delays) and estimated the causal effect of the ordering on elicited time preferences. Respondents who considered the longer-delay questions exhibited more patience, and the effects were larger for women. Economists need to take into account the ordering effect as they design experiments by which to elicit time and other preferences
Birthweight as a measure of holiday stress
No full text© 2018 Taylor & Francis. Young wives in South Korea often dread New Year’s Day and Thanksgiving Day because they assume the burden of cooking, cleaning, and other household chores. We used their offspring’s birthweight as an indicator of their stress levels. We included all Korean singletons born in hospitals during 1997–2014 (N = 8,589,426) and regressed birthweight on in utero holiday experience by trimester, along with covariates. Babies who experienced New Year’s Day in the first trimester were 9.4 grams lighter than those who did not; the amount is equivalent to 120% of the reduced birthweight associated with experiencing landmine explosions during the first trimester in Colombia. Higher birthweight was related to being in the first trimester during Thanksgiving Day versus not. However, experiencing this holiday during the third trimester was associated with less increase in birthweight than during the other trimesters. These results suggest that the New Year’s holiday may reflect stress for Korean women in their first trimester of pregnancy, resulting in reduced birthweight, but similar stress was not associated with the Thanksgiving Day holiday. Clinicians and policymakers should be aware of this potential high stress level among Korean women during New Year’s Day and seek ways to prevent and alleviate it
The risk preferences of entrepreneurs in Indonesia
No full text© 2016 Board of Trustees of the Bulletin of Economic Research and John Wiley & Sons Ltd.Entrepreneurship is known to be important for innovation and economic growth, but relatively little attention has been paid to entrepreneurs in developing countries. We examined an important aspect of entrepreneurship: risk-taking. We analysed the Indonesian Family Life Survey and compared risk preferences between entrepreneurs and non-entrepreneurs. We found that risk tolerant workers were more likely to be entrepreneurs than risk averse workers by about 5 percentage points, or about 20 percent of the proportion of entrepreneurs in the labour force. The results imply that not all entrepreneurs in Indonesia are pushed into the sector; some actively take risks and seek innovations
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