PhD defence D. (Di) Long

Below is a brief summary of the dissertation:

Population health is the summary of individual health in a population. For population health, the overall goal isto maintain and improve health in a population and eliminate the disparities within the population. To achieve this goal, it is important to measure population health and disparities, and report risks that are related to population health. Different health metrics can be used to measure objective and subjective health outcomes, and health inequalities. Populations with lower socioeconomic status are often associated with higher prevalence of ill-health. In order to effectively examine health inequality, it is important to use proper health metrics that can accurately report population health at different time periods. During the COVID-19 pandemic, population health may be heavily impacted. Therefore, it is crucial to report the level of population health and identify vulnerable populations that are at risk of health deteriorations.

The aim of this thesis was to gain more insight in measuring population health at times using different health metrics, address the validity of subjective health metrics, and explore the pattern of inequality, using objective and subjective population health metrics. This thesis consists of seven studies, divided in three parts that each address these research questions:

1. To what extent did the patterns of socioeconomic inequality in mortality evolve in the past century?
2. Were population health metrics for subjective health outcomes administered through web-based questionnaires reliable to measure population health?
3. What was the level of population health during the courses of the COVID-19 pandemic?