Research

Working Papers

“Do Minimum Wage Increases Induce Changes in Work Behavior for People with Disabilities? Evidence from AbilityOne Program"

• Abstract: We offer the first evidence on the effects of minimum wage increases on labor market outcomes for people with disabilities. We use a novel dataset consisting of quarterly data on employment, earnings, and hours for workers at firms that primarily employ people with disabilities, many of whom are paid subminimum wages. Exploiting recent local variation in minimum wage changes, we find that increasing the minimum wage does not affect employment outcomes for workers with disabilities, with precisely estimated null effects that rule out a perfectly competitive labor market model.

Work in Progress

"Income Shocks and Consumer Response: Evidence from the 2018-19 US Government Shutdown and SNAP Reimbursement Schedule Change"

Joint with Tatyana Avilova

"Marital Stability after Childbirth - Evidence from California's Paid Family Leave"

"Paid Family Leave and Parental Wage Gap around Childbirth"

"The Impact of Paid Maternity on Maternal Mental Health at Birth"

"Siblings' Year Spacing vs Grade Spacing: Effects on Parental Work and Time Use"

Publications

“Paid Family Leave and Fight Against Hunger – Evidence from New York"

• Abstract: We examine the effects of New York’s paid family leave (PFL) policy, introduced in January 2018, on food security. While researchers evaluating PFL policies in the past have mostly focused on employment and health outcomes, we believe that an improved understanding of potential impacts on food security is pivotal as it is directly related to the health and well-being of mothers and new-borns during the postnatal months. Our analysis uses two primary data sets – Current Population Survey Food Security Supplement (CPS-FSS) and Panel Study of Income Dynamics (PSID). Estimating difference-in-differences (DD) and triple difference (DDD) models, we show that New York’s PFL reduced the prevalence of low food security by 36% in both datasets. The positive effects are more sizable for households with low-educated heads and families with incomes under 185% of the Federal Poverty Line. These findings highlight that paid leave benefits lead to a larger reduction in food insecurity among disadvantaged families and thus have the potential to reduce existing societal inequalities. When examining potential mechanisms through which New York’s PFL law improves food security, we show that the policy increased food expenditures, increased labor force participation, particularly by mothers, and improved parental health.

"The Effects of Paid Family Leave – Does It Help Fathers’ Health, too?"

• • Abstract: I investigate the effects of California’s paid family leave (CA-PFL) program, the first state-mandated paid leave available to both mothers and fathers in the U.S. I examine the effects on the overall health of mothers and fathers during two distinct periods: health immediately around childbirth, and health following childbirth. To do so, I leverage the variation in the timing of the Survey of Income and Program Participation (SIPP) health care topical module relative to the exact year and month of childbirth. I find that CA-PFL has improved mothers’ health during pregnancy and immediately after childbirth. This improvement in health is accompanied by a reduced likelihood of mothers not working or taking unpaid work absence. Some improvements manifest in fathers’ health too during the same period. However, I observe that fathers report more instances of feeling sick, starting around five months after childbirth. Further analysis reveals that the share of fathers not working or taking unpaid work absence rises temporarily when the leave period ends. Understanding the effects on fathers’ health and leave utilization is pivotal to evaluating the program’s overall benefits and potential unintended consequences given the growing focus on enhancing equal access to paid leave for both mothers and fathers.

“Sibling Correlation in Educational Attainment: A Test of Genetic Nurture” 

• • Abstract: Health is strongly and positively correlated with education, which contributes to interest in the determinants of education. In this paper, we test for a specific type of family influence on education: genetic nurture. Specifically, we test whether a person’s educational attainment is correlated with their sibling’s polygenic score (PGS) for education, controlling for their own PGS. Models estimated using genetic data in the National Longitudinal Survey of Adolescent to Adult Health (Add Health) yield strong evidence of genetic nurture, which is robust to alternative measures of educational attainment and different measures of the polygenic score. An exploration of mechanisms suggests that older siblings influence their parents’ educational expectations for the younger children in the family.

“Extreme Temperatures during Pregnancy and Adverse Birth Outcomes: Evidence from 2009-2018 U.S. National Birth Data” 

• • Abstract: We provide the first estimates of the impacts of prenatal exposure to extreme temperatures on infant health at birth using the latest national birth data from 2009 to 2018 from all U.S. states. We consistently find that an additional day with mean temperature greater than 80 or less than 10 increases preterm births and low birthweight. Strikingly, the adverse effects are borne disproportionately by Black and Hispanic mothers, suggesting that the projected increase in extreme temperatures may further exacerbate the existing birth health disparities across different race/ethnicity groups. We also contribute by investigating the impact of deviations from the normal weather pattern, to identify the extreme weather events after accounting for the adaptation response. We find that prenatal exposure to extreme heat two standard deviations above county’s historic average induces preterm births and NICU admissions, particularly for mothers whose pregnancies overlap with summer months. These results are timely and policy relevant, considering the recent weather trends with rising temperatures and frequent extreme weather events.

“What to Expect When It Gets Hotter: The Impacts of Prenatal Exposure to Extreme Temperature on Maternal Health.” 

• • Media Coverage: Stanford Health Policy News,  Journalist’s Resource, Market Watch, MIT Technology Review, Lady Science
  • Abstract: We use temperature variation within narrowly-defined geographic and demographic cells to show that exposure to extreme temperature increases the risk of maternal hospitalization during pregnancy. This effect is driven by emergency hospitalizations for various pregnancy complications, suggesting that it represents a deterioration in underlying maternal health rather than a change in women's ability to access health care. The effect is larger for Black women than women of other races, suggesting that, without signicant adaptation, projected increases in extreme temperatures over the next century may further exacerbate racial disparities in maternal health.

“Targeting Using Differential Incentives: Evidence from a Field Experiment.” 

• • Abstract: The utilization of preventive health services remains low in developing countries, especially among the traditionally disadvantaged groups. Using a field experiment in Nepal, we investigate if differential incentives to health outreach workers help improve such utilization by disadvantaged groups. We varied the amount of financial incentives provided to health outreach workers by the ethnicity of the client they recruited for a free sugar-level assessment. We find that a differential incentive in the ratio of 2.5:1, geared toward encouraging a disadvantaged referral, raises the chances of such referral by 11.6 percentage points. This effect translates to an incentive elasticity of referral of about 0.2. There is no evidence that the outreach workers refer less healthy individuals to benefit from higher financial incentives. Conversely, on the demand side, we find no evidence that a financial incentive provided directly to a disadvantaged individual raises the uptake of preventive health services.

“Heterogeneous Impact of SNAP Benefit Changes on Food Security by Local Prices.” 

• • Abstract: The Supplemental Nutrition Assistance Program benefit amount is fixed across all 48 states (except Hawaii and Alaska), although food prices vary widely. Hence, the real value of SNAP benefits can directly affect the purchasing power of SNAP participants and subsequently their food insecurity. Using the 2 most recent changes to the SNAP benefit formula in 2009 and 2013, this study examines whether the changes in benefit level affected food security of participants differentially depending on local food prices. Using data from the Current Population Survey-Food Security Supplement 2008–2009 and 2012–2013, merged with the Regional Price Parities from the Bureau of Economic Analysis, we find that after the benefit increase, the prevalence of low food security among SNAP households living in high-cost areas declined by 11.2 percentage points. Following the benefit decrease, the prevalence of very low food security among SNAP households increased by 8.7 percentage points in high-cost areas. In contrast, there was no statistically significant difference between SNAP and non-SNAP households in low-cost areas in response to the benefit changes.

“Testing for Family Influences on Obesity: The Role of Genetic Nurture.” 

Health Economics 28(7): 937−952, June 2019

• • Abstract: A large literature has documented strong positive correlations among siblings in health, including body mass index (BMI) and obesity. This paper tests whether that is explained by a specific type of peer effect in obesity: genetic nurture. Specifically, we test whether an individual's weight is affected by the genes of their sibling, controlling for the individual's own genes. Using genetic data in Add Health, we find no credible evidence that an individual's BMI is affected by the polygenic risk score for BMI of their full sibling when controlling for the individual's own polygenic risk score for BMI. Thus, we find no evidence that the positive correlations in BMI between siblings are attributable to genetic nurture within families.

“Changes in Low-Income Households? Spending and Time Use Patterns in Response to the 2013 Sunset of the ARRA-SNAP Benefit.” 

• • Media coverage: USDA ERS Ambers Wave (August 2019)
  • Abstract: We examine the effects of the 2013 Supplemental Nutrition Assistance Program (SNAP) benefit cut on households’ food expenditures, as well as other expenditure categories by analyzing data from the 2012–2014 Consumer Expenditure Survey (CEX). Making use of the short panel structure of the CEX, we employ difference‐in‐differences methods with household fixed effects. Results show that reduced SNAP benefits significantly decreased the food‐at‐home expenditure of SNAP households, but increased expenditure on used cars and public transportation. To further explore these findings, we use the American Time Use Survey (ATUS), where we find that SNAP households spent less time on food preparation, but more time on market work (both formal work and informal work) after the 2013 SNAP benefit cut. Our findings suggest that cutting program benefits by any level is immediately reflected in low‐income household's food expenditure. Our results also indicate that an increase in transportation expenditures correspond with the observed increase in labor supply for participant households. These reveal important information about the behaviors and coping strategies of low‐income households as they respond to a negative shock to their income.

“The Effects of Temporal Aggregation on Search Engine Data.” 

• • Abstract: Through the use of structured machine learning, this paper examines the effects of temporal aggregation on big data from Google Analytics and Google Trends. Google Analytics is used to obtain daily and weekly tourism data from the Charleston Area Convention and Visitors Bureau (CACVB) website, and Google Trends is used to obtain an index formed from big data of weekly, monthly, and quarterly data for seven economic variables. Taking into account the different levels of aggregation, the CDFs and the estimated structured machine learning output are used to study the effects of temporal aggregation. The Kolmogorov-Smirnov test rejects the null of equivalent data distributions in the vast majority of cases for the CACVB data, but this is not the case for the economic variables. Through data mining techniques, this paper also finds that the level of aggregation has the potential of affecting the level of integration and the estimated structured machine learning output for both the CACVB data and the seven economic variables.

“The Timing of Exemptions from Welfare Work Requirements and its Effects on Mothers’ Work and Welfare Receipt around Childbirth.” 

• • Abstract: I quantify the effects of welfare work exemptions on women's labor force participation and welfare receipt. This study, which also examines the age of youngest child (AYC) exemption, is the first to investigate the pregnancy exemption. Between‐state and within‐state variations in exemption length allow me to estimate the heterogeneous effects of each exemption by its timing and strictness. I find that the effects on labor force participation are driven by employment for the pregnancy exemption, inducing relatively stable welfare receipts. In contrast, the effects are driven by unemployment for the AYC exemption, which triggers more reliance on welfare after birth.

“Effects of the 2013 SNAP Benefit Cut on Food Security.” 

• • Abstract: Effects of the 2013 Supplemental Nutrition Assistance Program (SNAP) benefit cut on food security is examined by employing the annual Current Population Survey Food Security Supplement 2012–2014. Food security measured in December 2014 is compared with the corresponding statistics for December 2012 using difference‐in‐differences methods. Results confirm that reduced SNAP benefits significantly threatened the food security of SNAP households.

“Do SNAP Participants Expand Non-Food Spending When They Receive More SNAP Benefits? ―Evidence from the 2009 SNAP Benefits Increase.” 

• • Media coverage: Wikipedia on Supplemental Nutrition Assistance Program, Washington Post
  • Abstract: This study examines the expenditure response to the largest increase in Supplemental Nutrition Assistance Program benefits, instituted in April 2009. Investigating the effects in both food and non-food spending categories, I find that the rise in SNAP benefits increased not only food at home expenditures, but also housing, transportation, and education expenditures of SNAP households relative to those of non-SNAP households. Specifically, the SNAP benefit increase leads to the reduced out-of-pocket spending on food for infra-marginal SNAP recipients, and the freed up resources allowed households with bounded budgets to fund other essential needs, such as paying mortgage, rent, utility fee, transportation expenses as well as tuition. Examining non-food expenditures provides a more complete picture of the impact of the SNAP benefit increase by shedding light on the spillover effect of the policy change. The result also derives policy implication on ongoing debate about SNAP allotment generosity.

“Measuring Poverty Using the Supplemental Poverty Measure in the Panel Study of Income Dynamics, 1998 to 2010.” 

• • Abstract: The Supplemental Poverty Measure (SPM) was recently introduced by the U.S. Census Bureau as an alternative measure of poverty that addresses many shortcomings of the official poverty measure (OPM) to better reflect the resources households have available to meet their basic needs. The Census SPM is available only in the Current Population Survey (CPS). This paper describes a method for constructing SPM poverty estimates in the Panel Study of Income Dynamics (PSID), for the biennial years 1998 through 2010. A public-use dataset of individual-level SPM status produced in this analysis will be available for download on the PSID website. Annual SPM poverty estimates from the PSID are presented for the years 1998, 2000, 2002, 2004, 2006, 2008, and 2010 and compared to SPM estimates for the same years derived from CPS data by the Census Bureau and independent researchers. We find that SPM poverty rates in the PSID are somewhat lower than those found in the CPS, though trends over time and impact of specific SPM components are similar across the two datasets.

“Are Household Food Expenditures Responsive to Entry Into the Supplemental Nutrition Assistance Program?” 

• • Abstract: This study examines changes in household food expenditures in the months directly around entry into the Supplemental Nutrition Assistance Program (SNAP). Using monthly data on SNAP participation from the Panel Study of Income Dynamics (PSID), we estimate food‐expenditures‐to‐food‐needs ratio with an event‐study specification. Upon entering the program, a substantially lower share of out‐of‐pocket spending accounts for SNAP households’ food budgets. However, these expenditures are largely replaced with SNAP benefits, resulting in little changes in total food expenditures. We also identify the co‐occurrence of household economic shocks at the point of SNAP entry. SNAP entry is preceded by reduced rates of employment and marriage among heads of households, suggesting that household economic shocks may trigger SNAP entry. We find that SNAP benefits visibly appear to act as an important safety net for households who have recently entered the program, cushioning them from the extent of a negative shock in food expenditures that they might otherwise have faced.

Other Publications

“A Win for the War on Child Poverty"

“SNAP Households Adjust Their Expenditures and How They SpendTheir Time in Response to Changes in Program Benefits." 

Amber Waves Magazine, USDA ERS 2019

Joint with Matthew Rabbit

“An Updated Method for Calculating Income and Payroll Taxes from PSID Data Using the NBERʼs TAXSIM, for PSID Survey Years 1999 through 2011." 

Media Interviews

“A Conversation with Jiyoon (June) Kim"

“As pandemic benefits wind down, a reckoning for households and economy" 

Washington Post, April 2023