林明仁 Ming-Jen Lin​

We used a nationwide demographic survey to study the relation between television exposure and women’s empowerment in India. Ordinary least squares (OLS) results suggested that TV exposure improved Indian women’s status. We used the propensity score matching (PSM) method to mitigate the potential threat of endogeneity. The results indicate that TV exposure is correlated with greater awareness of autonomy, greater financial independence, less unwanted pregnancy (birth control), negative attitude toward beating, a lower tendency of giving birth, a smaller family, and a lower preference level for sons.

OBJECTIVE:
Mothers sero-positive for hepatitis B are slightly more likely to have a son. It is not known whether it is ever having HBV (HBsAg[+]) or currently active HBV (HBeAg[+]) which is associated with having a son.
METHOD:
Multivariable linear regression was used to assess the adjusted association of HBeAg(+) with offspring sex in all (90%) births (~3 million) in Taiwan from 1988 to 1999.
RESULTS:
Totally, 5% of mothers were HBeAg(+). HBeAg(+) mothers were slightly more likely to have a son (sex ratio 108 rather than 106) adjusted for HBsAg, birth order, mother's age, birth year, and area of residence.
CONCLUSION:
At a population level HBV status makes little difference to the sex ratio at birth.

Using national data of the male population (a total of 715,000 observations) in Taiwan, this study finds a significant association between LBW and the probability of committing crime appears exclusively among those born to mothers under 18 or over 40 at the time of childbearing. Moreover, this association occurs particularly in violent crime. The interaction between biological and demographic factors suggests that being born to very old or young mothers and LBW together may create a double hazard of biological disadvantage, leading to higher risk of committing violent crime later. The other side of the coin is that, regarding to violent crime, being born low birth weight may not be a disadvantage unless it is triggered by certain adversity.

By combining two unique Taiwanese datasets, this paper investigates how birth weight affects grades at age 15 years. To tackle the endogeneity problem caused by omitted variables, we first compare birth weight and grade variation within twins. We find that birth weight does increase grades but only when both twins weigh less than 3000g at birth, which indicates that the effect is non-linear, and when the weight difference between the twins is larger than 200g. Furthermore, twin fixed effect estimates are similar to the ordinary least squares (OLSs) ones. We then use the public health budget and the number of doctors in the county where the children were born as instrumental variables for the children's birth weight. We found that instrumental variable estimates are significant only for the less educated (<9 years) and young (<25 years) mothers. We conclude that the effect of birth weight is real and non-linear and its effect on less educated and young mothers is the most severe. Furthermore, the bias produced by OLS may not be large if the correct subgroup of the population has been identified.

Economic theory suggests police and crime are negatively correlated. However, it is surprisingly difficult to demonstrate this relation empirically, as areas with greater numbers of crimes tend to hire more police. In order to resolve this simultaneity, we begin by exploring the structure of the financial relationship existing between state and local governments, arguing that variations in state tax rates can serve as an instrumental variable for local police numbers. Two-stage least square (2SLS) result show that the elasticity of police presence with respect to crime is about −1.1 for violent crime, and −0.9 for property crime. These results are mostly significant, and are more negative than those obtained under OLS. Overall, our estimations suggest that police does reduce crime.