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Three new postdoctoral fellows introduced themselves and their research at this fall’s kickoff brown-bag seminar at the University of Michigan Population Studies Center (PSC). Here’s a look at their work.

Nathan Franz: Untangling India’s Health Data Puzzles

Nathan Franz joins the Population Studies Center after earning his PhD in economics from UT Austin, launching his research on maternal and child health in India through the lenses of health systems and statistical measurement. 

Franz’s job market paper tackled a conspicuous puzzle: “Private facilities [in rural North India] have more advantaged patients, and they charge more money,” he said, “but more of their newborns die, compared to public facilities.”

Using econometric selection models and a geographic regression discontinuity design, Franz’s work showed this is a problem driven by quality of care. He’s now extending this work to examine how the effect varies across caste and religious groups, and how regulatory capacity might predict similar disparities across states and countries.

On the measurement side, Franz investigates whether we can trust the data underlying India’s public health statistics. In one project, he and Sangita Vyas used children’s height—a biological marker sensitive to fecal pathogen exposure—to test whether a major government sanitation campaign actually reduced open defecation, finding reason for skepticism about self-reported survey data. 

In a study with Austin’s Diane Coffey, Aashish Gupta, and Dean Spears, he showed that India’s Demographic and Health Surveys suggest maternal mortality rates far higher than official government estimates. Franz found that India’s official demographic statistics show implausibly low statistical noise—less variation than the reported survey methods should produce—raising questions about how these numbers are generated.

Franz’s postdoc mentors at PSC will be Hoyt Bleakley and Dean Yang.

Jessie Himmelstern: Where Work and Health Collide

Jessie Himmelstern comes to PSC from the University of Minnesota, to work under mentors Sarah Burgard and Belinda Needham. Her academic path included a sociology degree from American University, a master’s from NYU, and several years as a market researcher before returning to graduate school.

Himmelstern’s research sits at the intersection of labor market inequality and population health. Using Current Population Survey data (1978 to 2022), she developed two new measures of job insecurity: an “insecurity rate” tracking how many people experience unstable employment, and an “insecurity depth” measure capturing how severe that instability is. Her findings reveal that fewer workers overall are experiencing employment insecurity, but those who do face increasingly intense disruption, especially since the Great Recession.

In other research, Himmelstern co-authored a paper with Elizabeth Wrigley-Field of Minnesota directly confronting claims that COVID-19 was comparable to the flu. Their comparison of cumulative death rates calculated how many years of flu and pneumonia deaths would be needed to equal the toll of the COVID pandemic between March 2020 and February 2023. Their finding in a nutshell: “COVID is a lot worse.” For all states other than Hawaii, which had an exceptionally high rate of flu deaths in that time period, at least 9 to 21 years of flu and pneumonia were needed to match COVID-19. For the United States as a whole, 17 years of flu and pneumonia deaths are needed to match the death toll of the pandemic.

Himmelstern’s dissertation asked how health affects job prospects. Using an audit study with fabricated resumes, she found that applicants with employment gaps due to their own health fared significantly worse than a fully-employed control group. Surprisingly, this work also found that general unemployment gaps and family-caregiving gaps didn’t significantly hurt candidates’ chances, challenging assumptions about how “scarring” unemployment truly is in today’s labor market.

Michael Topping: Place, Position, and Time in Health Disparities

Michael Topping, who trained in demography and sociology at the University of Wisconsin, has joined PSC and the Stone Center for Inequality Dynamics to work with Pam Herd and Robert Manduca.

“I study broadly health disparities or health heterogeneity,” Topney said. “I specifically think about how place, position, and time work independently and interactively to shape these disparities.”

His research reveals that the well-known “rural mortality disadvantage” isn’t universal—it’s concentrated among white Americans and residents of the South, while many non-white populations outside the South actually show a rural advantage in life expectancy. These dynamics have changed over time. Once driven by differences in death rates from external causes, the rural disadvantage today, according to Topping, is increasingly about people in urban areas surviving chronic disease to older ages, likely reflecting the erosion of rural healthcare infrastructure.

Topping’s project examining cognitive life expectancy by birthplace, using Bayesian multi-state modeling, shows Southern-born Americans face a “dual penalty”: Shorter overall lifespans and a greater share of those years lived with cognitive impairment or dementia. Non-white and less-educated individuals show even starker gaps. Topping is now investigating whether this Southern disadvantage has eroded across cohorts amid sweeping educational and economic changes— with implications for how we think about place-based health policy.

PSC is one of the oldest population centers in the United States, with a distinguished 60-year record of domestic and international research and training in population dynamics. The center administers a large training program for both predoctoral and postdoctoral scholars, to cultivate  the next generation of population health scientists. Support for our training program is provided by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and the National Institute on Aging (NIA).

This post was written by Tevah Platt, communications manager for the Population Studies Center.