Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 238 for “"observational studies"”.
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Observational studies of highly evolved cataclysmic variables
Cataclysmic Variables (CV) are binary systems where a main-sequence star transfers mass onto a white dwarf (WD). According to standard evolutionary theory, angular momentum loss drives CVs to initially evolve from longer to shorter orbital periods until a minimum period is reached (? 80 minutes). …
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Observational studies of key stages in stellar evolution
This thesis presents observational investigations into three poorly-understood, but key stages in stellar evolution. Stars undergoing the post T Tauri phase - which lies between the well-studied T Tauri stage of disc accretion and the arrival onto the Main Sequence - are difficult to identify and …
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Uplift modeling for randomized experiments and observational studies
… the uplift modeling problem in the context of observational studies. In observational studies. treatment selection is influenced by subject characteristics. As a result. baseline characteristics often differ systematically between different treatments. Thus confounding factors need to be …
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Observational Studies of Rare Quasar Outflows: the FeLoBALs
The absorption spectra of quasar outflows are studied in order to determine their kinematic and energetic properties and how they affect their host galaxy and its surroundings. If an outflow is sufficiently powerful to have an effect, a process known as active galactic nucleus (AGN) feedback, it …
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Representation Learning Based Causal Inference in Observational Studies
… approaches for causal effect estimation in observational settings, where controlled experimentation is infeasible and confounding is the main hurdle in estimating causal effect. As such, deconfounding constructs the main subject of this dissertation, that is (i) to restore the covariate …
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What motivates patients to remain in longitudinal observational studies?
… rates threaten the validity of clinical research studies and generalizability of the results.</p> <p>Aims: To survey Hepatitis B Research Network (HBRN) Cohort Study participants to evaluate University of Michigan retention strategies, to develop best practices, and to identify other strategies …
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Observational Studies of Software Engineering Using Data from Software Repositories
Data for empirical studies of software engineering can be difficult to obtain. Extrapolations from small controlled experiments to large development environments are tenuous and observation tends to change the behavior of the subjects. In this thesis we propose the use of data gathered from …
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Auditory Alarms In The Intensive Care Unit: Experimental And Observational Studies
… environment when alarms are activated, two observational studies were undertaken. The first study used a video camera and the second study involved direct observation using two observers. A series of tasks were developed that used the multiple resources literature as a framework and also …
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Essays on Propensity Score Methods for Causal Inference in Observational Studies
… scores in drawing causal inferences in observational studies. </p><p>Chapter 1 talks about the general idea of causal inference as well as the concept of randomized experiments and observational studies. It introduces the three different projects and their contributions to the …
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Methods for observational studies using data from massive open online courses
… and other confounding variables that arise in observational studies like this, as each student decides what components they engage in throughout the course. This method is applied to an edX course, 6.002x, to estimate the effect of attempting homework and other assessments on students' final …
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Causal Inference with Measurement Errors: with Applications to Experimental and Observational Studies
… the existence of measurement errors in their studies. As a result, they sometimes fail to adjust for them. By combining tools drawn from the literature on machine learning, causal inference, and measurement errors, this dissertation illustrates the existence of measurement errors in these …
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Laboratory and Observational Studies of Transient Molecules at Microwave and Millimeter/Submillimeter Wavelengths
In this dissertation, techniques of high-resolution rotational spectroscopy have been used to measure the spectra of molecules in both laboratory and astronomical settings. In the laboratory, small metal-bearing molecules containing zinc, iron, nickel, titanium, yttrium, and scandium have been …
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Observational studies of scatterometer ocean vector winds in the presence of dynamic air-sea interactions
… Given the conclusions of these individual studies, this work collectively solidifies decades of theory and validates the use of scatterometer winds in areas of complex air-sea interaction.</p>
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Robust sensitivity analysis for quantiles of hidden biases and treatment effects in matched observational studies
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-12-01
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Modeling and Observational Studies of Shallow Cumulus Convection Over the Indian Ocean: Aerosol and Meteorological Effects on Diurnal Cycles
Additional solar heating induced by soot aerosols affected the static stability in the boundary layer. The vertical profile of soot aerosols had a critical influence on how they impacted cloud properties and turbulence. Changes in environmental relative humidity and the presence of a dry and stable …
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Effects of Anthropogenic Urea on Lakes of the North American Great Plains: Ecological Implications Based on Experimental and Observational Studies
Urea consumption has increased dramatically since the 1960s and now comprises over 50% of the nitrogen (N)-based fertilizer used globally. Currently, only 30-50% of N-fertilizers applied to cropland are effectively used by crops, while the remainder is lost to the environment. Urea is also a …
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Causal Effect Random Forest Of Interaction Trees For Learning Individualized Treatment Regimes In Observational Studies: With Applications To Education Study Data
… individualized treatment regimes (ITR) using observational data holds great interest in various fields, as treatment recommendations based on individual characteristics may improve individual treatment benefits with a reduced cost. It has long been observed that different individuals may …
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