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Abstract:
In this note, we address several issues in the Fowler and Christakis (FC) comment on our JHE paper (CCF). This type of situation is conducive to vigorous academic debate - and we appreciate a number of the points that FC raise about our study. Several points are potentially valid and could benefit from in-depth discussion. However, a second aspect the FC paper is the inclusion of slights that speak both to our professional conduct and competence and move beyond professional debate. We address both the issues raised about our results and further clarify additional aspects of the FC comment. We further note that regardless of the points of dispute between CCF and FC, the FC results should not be thought of as causal because FC provides no empirical solution to the reflection problem.

Peer Effects, Obesity

Abstract:
In this paper, I examine the current policy of full inclusion of children receiving special education services into regular education classrooms. Specifically, this paper focuses on the policy's effects on the classmates of children with special needs, with a particular focus on classmates of students with serious emotional problems. Results suggest that students with a classmate with a serious emotional problem experience reductions in first grade test scores, especially students in low-income schools. Results that attempt to capture sorting across and within school, using school-level random and fixed effects specifications and matching estimation, are qualitatively similar. The magnitude of the reduction in mathematics achievement is similar to the adjusted achievement gap between Hispanic and white students and 30%-50% of the size of the adjusted black-white gap. Since nearly 10% of the student population has a classmate with a serious emotional problem, the aggregate effect on test scores of the policy of inclusion of these students is potentially quite large.

Inclusion, Peer Effects, Special Education

Abstract:
This note's aim is to investigate the sensitivity of Christakis and Fowler's claim (NEJM July 26, 2007) that obesity has spread through social networks. It is well known in the economics literature that failure to include contextual effects can lead to spurious inference on social network effects. We replicate the NEJM results using their specification and a complementary dataset. We find that point estimates of the social network effect are reduced and become statistically indistinguishable from zero once standard econometric techniques are implemented. We further note the presence of estimation bias resulting from use of an incorrectly specified dynamic model.

Obesity, Peer Effects, Social Networks

Abstract:
Childhood and adolescent obesity is associated with serious lifetime health consequences and has seen a recent rapid increase in prevalence. Soft drink consumption has also expanded rapidly, so much so that soft drinks are currently the largest single contributors to energy intake. In this paper, we investigate the potential for soft drink taxes to combat rising levels of adolescent obesity through a reduction in consumption. Our results, based on state soft drink sales and excise tax information between 1988 and 2006 and the National Health Examination and Nutrition Survey, suggest that soft drink taxation, as currently practiced in the United States, leads to a moderate reduction in soft drink consumption by children and adolescents. However, we show that this reduction in soda consumption is completely offset by increases in consumption of other high calorie drinks.

obesity, soft drink taxation

Abstract:
In this paper, I use a social interactions framework to detect whether individual smoking decisions are influenced by classmate smoking decisions. There are several large challenges in addressing this question, including the endogeneity of school (and thus classmates) through residential location choices, 'third factors' such as school-level unobservables that influence individual and classmate choices simultaneously, and the difficulty of the identification of parameters in empirical models of social interactions (Manski 1993, Brock and Durlauf 2001). In order to address these issues, I use an instrumental variables/fixed effects methodology that compares students in different grades within the same high school who face a different set of classmates and classmates' decisions. Preferred specifications suggest that increasing the proportion of classmates who smoke by 10% will increase the likelihood an individual smokes by approximately 3 percentage points. I compare these results with previous findings that are unable to use school fixed effects and/or use potentially invalid instruments and find that the current results suggest smaller social interactions in adolescent smoking decisions than some previous work.

Peer Effects, Social Interactions, Smoking

Abstract:
In this paper, I use nationally representative longitudinal data to examine adolescent depression and educational attainment. First, I examine the individual, family, and community-level determinants of adolescent depression, diagnosis, and treatment. I find that male and minority adolescents who score high on depression scales are less likely to be diagnosed as depressed or receive treatment than female and non-Hispanic white adolescents. Additionally, I find several community-level variables to be important determinants of depression, diagnosis, and treatment. Second, I examine the importance of adolescent depression for educational attainment. Although it is uncontroversial to expect a negative relationship, most previous research uses cross-sectional data, making it difficult to adequately determine the magnitude of the effect. I find that depressive symptoms are related to educational attainment along multiple margins: dropping out of high school, college enrollment, and college type. These relationships are only found for adolescent females, and there are several interesting results across income groups. Overall, these findings suggest that further attempts to diagnose and treat adolescents with depressive symptoms are needed and that additional treatment options may be required to combat the important relationship between adolescent depression and human capital accumulation for females.

Depression, Education, Mental Health

Abstract:
Background
Current methods used in medical literatures to estimate social network effects of health outcomes may be biased to find these effects, even if none actually exist.

Objective
To investigate whether we detect network effects for health outcomes that are unlikely to be subject to network phenomena.

Design
Our methods include statistical analysis now common in network studies such as logistic regression analysis with own and friend's lagged health status controlled. We extend the analysis by controlling for environmental confounders.

Setting
Sub-samples of the National Longitudinal Study of Adolescent Health (Add Health).

Participants
Between 4,300 and 5,400 male and female adolescents who nominated a friend in the dataset and who were both longitudinally surveyed.

Measurements
Health outcomes, including headache severity, acne severity, and height were self-reported by respondents in 1994/5, 1995/6, and 2000/1.

Results
We find statistically significant network effects in the acquisition of acne, headaches and height. A friend's acne problems increased an individual's odds of acne problems (OR: 1.47, 95% confidence interval [0.93-2.33]). The likelihood that an individual has headaches also increases with the presence of a friend with headaches (OR: 1.62 [0.91-2.89]). An individual's height increases by 20% of his/her friends' height [0.15-0.26]. Each of these results was estimated using standard methodology found in several publications in leading medical journals such as the New England Journal of Medicine and other outlets. However, once environmental confounders are controlled, the results become uniformly smaller and insignificant.

Conclusions
Caution is suggested in attributing correlations in health outcomes of close friends to social network effects, especially when environmental confounders are not adequately controlled in the analysis.

Peer Effects, Social Networks, Health

Abstract:
We examine whether the job characteristics of physical demands and environmental conditions affect individual’s health. Five-year cumulative measures of these job characteristics are used to reflect findings in the biologic and physiologic literature that indicate that cumulative exposure to hazards and stresses harms health. To create our analytic sample, we merge job characteristics from the Dictionary of Occupational Titles with the Panel Study of Income Dynamics dataset. We control for early and lagged health measures and a set of pre-determined characteristics to address concerns that individuals self-select into jobs. Our results indicate that individuals who work in jobs with the ‘worst’ conditions experience declines in their health, though this effect varies by demographic group. For example, for non-white men, a one standard deviation increase in cumulative physical demands decreases health by an amount that offsets an increase of two years of schooling or four years of aging. We also find evidence that job characteristics are more detrimental to the health of females and older workers. Finally, we report suggestive evidence that earned income, another job characteristic, partially cushions the health impact of physical demands and harsh environmental conditions for workers. These results are robust to inclusion of occupation fixed effects.

Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Abstract:
We present what we believe are the best estimates of how job characteristics of physical demands and environmental conditions affect individual's health. Five-year cumulative measures of these job characteristics are used to reflect findings in the physiologic literature that cumulative exposure is most relevant for the impact of hazards and stresses on health. Using data from the Panel Study of Income Dynamics we find that individuals who work in jobs with the 'worst' conditions experience declines in their health, although this effect varies by demographic group. For example, for non-white men, a one standard deviation increase in cumulative physical demands decreases health by an amount that offsets an increase of two years of schooling or four years of aging. Job characteristics are found more detrimental to the health of females and older workers. These results are robust to inclusion of occupation fixed effects, health early in life and lagged health.

Health, Occupational Characteristic

Abstract:
We use data from the National Longitudinal Study of Adolescent Health (Add Health) to examine the effects of classmate characteristics on economic and social outcomes of students. The unique structure of the Add Health allows us to estimate these effects using comparisons across cohorts within schools, and to examine a wider range of outcomes than other studies that have used this identification strategy.

We find that increases in the percent of classmates whose mother is college educated has significant, desirable effects on educational attainment and substance use. We do not find much evidence that the percent of classmates who are black or Hispanic has negative effects on individual outcomes, on average, but increases in the percent black or Hispanic does increase drop out rates among black students.

Education, Peer Effects, Cohort Study, Substance Abuse

Abstract:
This paper contributes to the literature on the relationship between adolescent depression and educational attainment in several ways. First, while cross sectional data are normally used to assess the importance of the relationship, this paper uses longitudinal data in order to defend against the potential of reverse causality. Second, this is the first paper in the literature to control for sibling fixed effects in examining the relationship between adolescent depressive symptoms and human capital accumulation. Importantly, this eliminates omitted factors such as family and neighborhood characteristics common to siblings that affect both depressive symptoms and educational attainments (e.g. neighborhood crime, family resources). Third, this paper examines the effects of both an indicator and scale of depressive symptoms and finds important associations with these depressive symptoms and human capital accumulation. Though not always precisely estimated, the results suggest that depressive symptoms decrease years of schooling, mainly through increasing the chances of dropping out but may have small impacts on the likelihood of college attendance (conditional on high school graduation). In particular, preferred estimates suggest that a standard deviation increase in depressive symptoms is associated with a 25-30% increase in the likelihood of dropping out.

Human Capital, Health, Depression, Fixed Effects

Abstract:
Whether giving birth as a teenager has negative economic consequences for the mother is a question that has been the topic of a substantial body of research, yet the answer remains controversial. In this paper, we build upon existing literature, especially the literature that uses the experience of teenagers who had a miscarriage as the appropriate comparison group. We show that miscarriages are not random events, but rather are likely correlated with (unobserved) community-level factors, casting some doubt on previous findings. Including community-level fixed effects in our specifications led to important changes in our estimates. By making use of information on the timing of miscarriages as well as birth control choices preceding the teenage pregnancies we construct more relevant control groups for teenage mothers. We find evidence that teenage childbearing likely reduces the probability of receiving a high school diploma by 5 to 10 percentage points, reduces annual income by $1,000 to $2,400, and may increase the probability of receiving cash assistance and decrease years of schooling.

Teenage Childbearing, Human Capital

Abstract:
The question of whether childhood mental illness has long term consequences in terms of criminal behavior has been little studied, yet it could have major consequences for both the individual and society more generally. In this paper, we focus on Attention-Deficit/Hyperactivity Disorder (ADHD), one of the most prevalent mental conditions in school-age children, to examine the long-term effects of childhood mental illness on criminal activities, controlling for a rich set of individual, family, and community level variables. The empirical estimates show that children who experience ADHD symptoms face a substantially increased likelihood of engaging in many types of criminal activities. An included “back-of-the-envelope” calculation of the social costs associated with criminal activities by individuals with childhood ADHD finds the costs to be substantial.

Mental Illness, ADHD, Crime, Sibling Fixed Effects

Abstract:
It is well documented that mental health outcomes are correlated between spouses. There are several alternative hypotheses for this correlation, including both causal and non-causal pathways. In this paper, I use an instrumental variables/fixed effects approach to examine whether there is evidence that an individual's mental health status spills over on his or her spouse's mental health status. Results from the IV-FE specifications that use spousal job problems as an instrument are large in magnitude. In particular, spousal mental health status is estimated to have a greater influence on an individual's mental health status than own mental health endowment and is similar in magnitude with own physical health status. Although not conclusive, these findings suggest that within-family spillovers of mental illness could be economically important and that policies that reduce mental health problems for individuals likely have unmeasured benefits for their family members.

Mental Health, Spousal Spillovers, Peer Effects

Abstract:
Occupation is discussed as a social determinant of health. Occupation has received little attention in this light in the economics literature. We examine occupation in a life-course framework and use measures of first-occupation, initial health, and mother's education. We contend that first occupation is a choice made relatively early in life that affects health outcomes at later ages. We examine first-occupation for two reasons: 1) there is growing evidence that early determinants affect later health and occupation has received little attention in this regard and 2) first occupation is predetermined in analysis of later health, which helps to address the issue of potential simultaneity. Using data from the Panel Study of Income Dynamics (PSID) we estimate the impact of initial occupation on two measures of health later in life: respondent-reported fair/poor health and ever suffering a heart attack. The PSID offers the opportunity to examine a lifecycle perspective as we can examine the impact of early occupation on later health while controlling for several predetermined conditions such as mother's education and health in youth. Estimates suggest that first-occupation has a durable impact on later health, ceteris paribus, but that the impact varies by health measure and the set of control variables in regression specifications. Early choice of occupation could be a critical factor in successful aging and this information may pave the way to developing more effective workplace and public policies to improve health in older ages.

Abstract:
The existence of a "marriage tax," in which many married couples pay more taxes when married than their combined taxes as single individuals, is well known. However, largely lost in the attention devoted to married taxpayers is the treatment of single taxpayers. This article examines the relative tax treatment of single and married taxpayers. Various types of representative taxpayers are constructed, and the difference in income taxes paid by single taxpayers and married taxpayers is calculated. These calculations show that there is a "singles tax"; that is, a single individual typically pays a greater income tax liability than a married couple with identical income, especially when the main transfer programs are considered.

Abstract:
The question of whether giving birth as a teenager has negative economic consequences for the mother remains controversial despite substantial research. In this paper, we build upon existing literature, especially the literature that uses the experience of teenagers who had a miscarriage as the appropriate comparison group. We show that miscarriages are not random events, but rather are likely correlated with (unobserved) community-level factors, casting some doubt on previous findings. Including community-level fixed effects in our specifications lead to important changes in our estimates. By making use of information on the timing of miscarriages as well as birth control choices preceding the teenage pregnancies we construct more relevant control groups for teenage mothers. We find evidence that teenage childbearing likely reduces the probability of receiving a high school diploma by 5 to 10 percentage points, reduces annual income as a young adult by $1,000 to $2,400, and may increase the probability of receiving cash assistance and decrease years of schooling.

Abstract:
Recently, Currie and Stabile (2006) made a significant contribution to our understanding of the influence of ADHD symptoms on a variety of school outcomes including participation in special education, grade repetition and test scores. Their contributions include using a broad sample of children and estimating sibling fixed effects models to control for unobserved family effects. In this paper we look at a sample of older children and confirm and extend many of the JCMS findings in terms of a broader set of measures of human capital and additional specifications.

Abstract:
Over the last decade, the federal government has directed schools to provide educational instruction for students with special needs in general education setting to the extent possible. While there is mixed evidence on the effects of these inclusion policies on the students with special needs, research examining potential spillovers of inclusion on non-disabled classmates has been scarce. There is particularly little research on the effects of inclusion policies on classmates during early elementary grades. This paper begins to fill in this gap by using a nationally representative, longitudinal survey of Kindergarteners. Cross sectional results suggest that having a classmate with an emotional problem decreases reading and math scores at the end of Kindergarten and first grade by over 10% of a standard deviation, which is 1/3 to 1/2 of the minority test score gap. In order to control for non-random sorting of students to schools as well as students to classrooms, this paper uses school-level and then student-level fixed effects. Results from the preferred empirical models suggest a decrease of approximately 5% of a standard deviation in math and reading scores, though the results are reading are less robust. The results also indicate moderate racial and gender differences in the effects.

inclusion, peer effects, special education, elementary school

Abstract:
Objective To examine whether social interactions influence the television viewing choices of adolescents in grades 7 through 12.

Design Data from a nationally representative cross-sectional survey were used to examine the association between individual-level and school-level television choices. An instrumental variables approach was used to solve the simultaneity problem found in models that examine the association between individual and aggregate choices. In-home interviews in the United States collected in 1996.

A sample of 4532 students in grades 7 through 12 in 132 US public and private schools who participated in the National Longitudinal Study of Adolescent Health (Add Health). The reported television viewing choices of an individual's schoolmates. The number of hours of television individuals reported viewing in a week.

The number of hours of television that adolescents report viewing per week was associated with their peers' reported hours of television viewing. Adjusted for other covariates, a 1-hour increase in average school-level television viewing was associated with an increase in almost half an hour of television viewing at the individual level.

Evidence suggests that social interactions within schools influence the hours of television that adolescents report viewing. This finding is important for both future attempts at modeling the determinants of adolescent television viewing and suggestions for future policy interventions. The presence of social interactions implies that interventions that affect the social norms of television viewing within schools could also change individual television viewing. In reducing the number of hours of television watched, these interventions could also positively affect adolescent obesity, emotional problems, and academic achievement.

Social Interactions, Television, Media Use, Social Influences

Abstract:
In this article, I use a national sample of high school students to test for several types of social infl uences on the decision to have sexual intercourse. I find evidence of endogenous social interactions (social multipliers), where the propensity of an individual choosing to have sex varies with the average behavior in his or her school. Additionally, the magnitude of the social multipliers and several other interesting risk factors differ by gender and by race. These findings might help explain the large variation in sexual initiation across schools in the United States. These results also add to the debate over school vouchers and ability grouping because social multipliers imply changes in schoolwide rates of sexual behavior with moderate changes in school-body composition. In this way, school vouchers and ability grouping might exacerbate the situation of high rates of teenage pregnancy and out-of-wedlock births in some communities. To show the potential benefi ts and costs of public policies that cause students to change schools, I present the results of several simulation exercises that predict the school-level changes in rates of sexual initiation following changes in school composition.

Sexual Initiation, Peer Effects

Abstract:
This paper estimates the price elasticity of demand for alcohol using Health and Retirement Survey data. To account for unobserved heterogeneity in price responsiveness, we use finite mixture models. We recover two latent groups, one is significantly responsive to price but the other is unresponsive. Differences between these two groups can be explained in part by the behavioral factors of risk aversion, financial planning horizon, forward looking and locus of control. These results have policy implications. Only a subgroup responds significantly to price. Importantly, the unresponsive group drinks more heavily, suggesting that a higher price could fail to curb drinking by those most likely to cause negative externalities. In contrast, those least likely to impose costs on others are more responsive, thus suffering greater deadweight loss yet with less prevention of negative externalities.

Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Abstract:
In this paper, we examine whether changes in housing costs lead to changes in rates of food insecurity for economically vulnerable families. We use data on a national, longitudinal sample of young families with children merged with data on housing (rental) costs at the state, MSA, and county levels (2001-2003). Focusing on families near or at the poverty level and using household fixed effects, we demonstrate that increased housing costs over this time period have indeed increased rates of food insecurity. Our preferred results suggest that a $500 increase in yearly rental costs is associated with nearly a 3 percentage point increase in food insecurity rates (10% relative increase). We show that our measure of rental costs seems to only affect the food insecurity of renters and not poor low-income home-owners, suggesting the validity of our methods and robustness of the findings. We also look at selected subgroups (e.g., food stamp recipients, individuals receiving housing subsidies) and find few differences in the effects of housing cost increases on food insecurity.

Food insecurity, Housing Costs, Expenditure Shocks

Abstract:
Recent literature has suggested that higher taxes on addictive goods could increase welfare by assisting individuals with self control problems and trouble resisting 'temptation'. In contrast, if individuals continue to use despite increased prices, taxation may serve to reduce the welfare of these individuals while providing no benefits in managing self control nor mitigating externalities. We use data on adolescents from the National Longitudinal Study of Adolescent Health (Add Health) to examine the impact of tobacco taxes on smoking. To account for unobserved heterogeneity in response to taxes we estimate finite mixture models, positing two types of individuals with differential responses to taxes. We find evidence of differential price elasticity for tobacco use across the adolescents groups, and show that individuals with low self control or high discount rates are largely unresponsive to cigarette price. Those who have the least willpower may need the most help in quitting but are unresponsive to taxes, suggesting that policies other than taxation may be needed to reduce adolescent tobacco use.

Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Abstract:
Drawing on findings from the biomedical literature, this paper introduces the idea that specific exogenously inherited differences in the genetic code between full biological siblings can be used to test within-family estimators and potentially improve our understanding of economic relationships. These points are illustrated with an application to identify the causal impact of several poor health conditions on academic outcomes. We present evidence of large impacts of poor mental health on academic achievement and demonstrate that our results are robust to reasonable violations of the exclusion restriction assumption. Further, our estimates suggest that family fixed effects estimators by themselves cannot fully account for the endogeneity of poor health.

Abstract:
In this paper, we provide some of the first empirical evidence of whether early occupational choices are associated with lasting effects on health status, affecting individuals as they age. We take advantage of data on occupational histories available in the Panel Study of Income Dynamics (PSID) to examine this issue. To the PSID data, we merge historical Census data that reflect the labor market conditions when each individual in the PSID made his first occupational choice. These data on labor market conditions (e.g. state-level share of blue collar workers) allow us to instrument for occupational choice in order to alleviate endogeneity bias. We use parental occupation as additional instruments. Since our instruments may have indirect effects on later health, we also control for respondent’s pre-labor market health, education and several family and state background characteristics in order to make the instruments more plausibly excludable. We find substantial evidence that a blue collar occupation at labor force entry is associated with decrements to later health status, ceteris paribus. These health effects are larger after controlling for endogeneity and are similar across sets of instruments. We also find differences in the effects of occupation by gender, race, and age.

Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Abstract:
While there is a well-established, large positive correlation between mental and physical health and education outcomes, establishing a causal link remains a substantial challenge. Building on findings from the biomedical literature, we exploit specific differences in the genetic code between siblings within the same family to estimate the causal impact of several poor health conditions on academic outcomes. We present evidence of large impacts of poor mental health on academic achievement. Further, our estimates suggest that family fixed effects estimators by themselves cannot fully account for the endogeneity of poor health. Finally, our sensitivity analysis suggests that these differences in specific portions of the genetic code have good statistical properties and that our results are robust to reasonable violations of the exclusion restriction assumption.

Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Abstract:
This paper examines the impact of job loss from business closings on body mass index (BMI) and alcohol consumption. We improve upon extant literature by using: exogenously determined business closings, a sophisticated estimation approach (finite mixture models) to deal with complex heterogeneity, and national, longitudinal data (Health and Retirement Study). For both alcohol consumption and BMI, we find evidence that individuals who are more likely to respond to job loss by increasing unhealthy behaviors are already in the problematic range for these behaviors before losing their jobs. Thus health effects of job loss could be concentrated among "at risk" individuals.

Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Abstract:
This report is based on a paper presented at the National Tax Associations's annual meeting, held November 16-19 in Boston.

The authors write that the demographic characteristics of a population have little influence on progressivity.