Economics Department Theses and Dissertations

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Browsing Economics Department Theses and Dissertations by Author "Boukai, Ben"

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    A Switching Regressions Framework for Models with Count-Valued Omni-Dispersed Outcomes: Specification, Estimation and Causal Inference
    (2020-02) Manalew, Wondimu Samuel; Terza, Joseph V.; Boukai, Ben; Osili, Una; Tennekoon, Vidhura; Trombley, Matt
    In this dissertation, I develop a regression-based approach to the specification and estimation of the effect of a presumed causal variable on a count-valued outcome of interest. Statistics for relevant causal inference are also derived. As an illustration and as a basis for comparing alternative parametric specifications with respect to ease of implementation, computational efficiency and statistical performance, the proposed models and estimation methods are used to analyze household fertility decisions. I estimate the effect of a counterfactually imposed additional year of wife’s education on actual family size (AFS) and desired family size (DFS) [count-valued variables]. In order to ensure the causal interpretability of the effect parameter as I define it, the underlying regression model is cast in a potential outcomes (PO) framework. The specification of the relevant data generating process (DGP) is also derived. The regression-based approach developed in the dissertation, in addition to taking explicit account of the fact that the outcome of interest is count-valued, is designed to account for potential sample selection bias due to a particular data deficiency in the count data context and to accommodate the possibility that some structural aspects of the model may vary with the value of a binary switching variable. Moreover, my approach loosens the equi-dispersion constraint [conditional mean (CM) equals conditional variance (CV)] that plagues conventional (poisson) count-outcome regression models. This is a particularly important feature of my model and method because in most contexts in empirical economics the data are either over-dispersed (CM < CV) or under-dispersed (CM > CV) – fertility models are usually characterized by the latter. Alternative count data models were discussed and compared using simulated and real data. The simulation results and estimation results using real data suggest that the estimated effects from my proposed models (models that loosen the equi-dispersion constraint, account for the sample selection, and accommodate variability in structural aspect of the models due to a switching variable) substantively differ from estimates from a conventional linear and count regression specifications.
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    Three Essays in Health Economics: Policy and Natural Shocks in Healthcare Provision and Patient Outcomes
    (2022-11) Shone, Hailemichael Bekele; Gupta, Sumedha; Royalty, Anne Beeson; Simon, Kosali; Tennekoon, Vidhura; Boukai, Ben
    Policy and natural shocks are exogenous factors, which may disrupt patients’ ability to access recommended health care. My dissertation investigates the effect of recent natural and policy shocks in health care provision on different patient outcomes. The first chapter studies the effect of the 2014 Ebola virus epidemic in West Africa on maternal health care utilization and infant health in Sierra Leone. The Epidemic resulted in the diversion of the limited health care resource away from other services to care for Ebola patients. It also led to maternal stress from fear of infection and community breakdown. The results show the outbreak led to significant decline in maternal health care utilization and infant birth weight. The second chapter examines whether physician practices that are vertically integrated with hospitals provide healthcare at higher costs than non-integrated practices in a Medicare patient population. The degree of integration is exogenously assigned to a patient following a geographical move. The study finds that switching to integrated practice increases health care utilization and spending. Although integration may increase quality of care, the increase in spending suggests the need for a continuing attention to policies and incentives that are associated with integration. Finally, the third chapter documents the impact of the recent changes in state medical and recreational cannabis access laws in the United States on health care utilization. The liberalization of access to cannabis may enable patients to substitute cannabis for another prescription and non-prescription health care services. The results show a significant decline in the utilization of emergency and outpatient services among patients with chronic pain for the states that legalized cannabis. The effect is mainly due to medical cannabis laws, whereas the effect of recreational cannabis is ambiguous. The three chapters, taken together, show that exogenous shocks, such as natural shocks and government policy, affect health care utilization and the health of individuals. Health policies should, therefore, target developing a resilient health care system that withstands natural shocks and promote policies that provide better treatment alternatives.