Educational researchers are often interested in phenomena that unfold over time within a person and at the same time, relationships between their characteristics that are stable over time. Since variables in a longitudinal study reflect both within- and between-person effects, researchers need to disaggregate them to understand the phenomenon of interest correctly. Although the person-mean centering technique has been believed as the gold standard of the disaggregation method, recent studies found that the centering did not work when there was a trend in the predictor. Hence, they proposed some detrending techniques to remove the systematic change; however, they were only applicable to multilevel models. Therefore, this dissertation develops novel detrending methods based on structural equation modeling (SEM). It also establishes the links between centering and detrending by reviewing a broad range of literature. The proposed SEM-based detrending methods are compared to the existing centering and detrending methods through a series of Monte Carlo simulations. The results indicate that (a) model misspecification for the time-varying predictors or outcomes leads to large bias of and standard error, (b) statistical properties of estimates of the within- and between-person effects are mostly determined by the type of between-person predictors (i.e., observed or latent), and (c) for unbiased estimation of the effects, models with latent between-person predictors require nonzero growth factor variances, while those with observed predictors at the between level need either nonzero or zero variance, depending on the parameter. As concluding remarks, some practical recommendations are provided based on the findings of the present study. / Doctor of Philosophy / Educational researchers are often interested in longitudinal phenomena within a person and relations between the person's characteristics. Since repeatedly measured variables reflect their within- and between-person aspects, researchers need to disaggregate them statistically to understand the phenomenon of interest. Recent studies found that the traditional centering method, where the individual's average of a predictor was subtracted from the original predictor value, could not correctly disentangle the within- and between-person effects when the predictor showed a systematic change over time (i.e., trend). They proposed some techniques to remove the trend; however, the detrending methods were only applicable to multilevel models. Therefore, the present study develops novel detrending methods using structural equation modeling. The proposed models are compared to the existing methods through a series of Monte Carlo simulations, where we can manipulate a data-generating model and its parameter values. The results indicate that (a) model misspecification for the time-varying predictor or outcome leads to systematic deviation of the estimates from their true values, (b) statistical properties of estimates of the effects are mostly determined by the type of between-person predictors (i.e., observed or latent), and (c) the latent predictor models require nonzero growth factor variances for unbiased estimation, while the observed predictor models need either nonzero or zero variance, depending on the parameter. As concluding remarks, some recommendations for the practitioners are provided.

Thesis advisor: Sara M. Moorman / This dissertation explores the complex relationship between social capital and depressive symptoms across the life course, focusing particularly on the increasing prevalence of depression from mid-to-late life. Using a life course perspective, this research investigates how social determinants, such as social capital, shape the emergence, increase, and decrease of depressive symptoms as individuals age. Drawing from both the tangible and psychological dimensions of social capital, this dissertation examines how changes in social connections and networks influence depressive symptom outcomes, including the biosocial consequences of depression on cognitive function in later life. The research is divided into three analytical papers. The first paper analyzes longitudinal data to assess the association between social capital and depressive symptoms, distinguishing between within- and between-person effects. The second paper explores how depressive symptom subtypes evolve from midlife to later life, identifying distinct subtypes and examining the stability and transitions between them over time. The third paper investigates the relationship between depressive symptom subtypes, social capital, and cognitive function, exploring how depressive symptom subtypes may mediate this association. Findings across these studies emphasize the pivotal role of social capital in shaping depression outcomes, highlighting how social isolation and disconnection may exacerbate depressive symptoms in later life. This dissertation contributes to the sociology of mental health and aging by offering new insights into the social mechanisms underlying depression and its long-term impacts on cognitive function. Through this work, policymakers and health professionals may gain a deeper understanding of how targeted interventions aimed at enhancing social capital could mitigate the global burden of depression in aging populations. / Thesis (PhD) — Boston College, 2024. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Sociology.

Genetic association studies usually include related individuals. Meanwhile, high-throughput sequencing technologies produce data of multiple genetic variants. Due to linkage disequilibrium (LD) and familial relatedness, the genotype data from such studies often carries complex correlations. Moreover, missing values in genotype usually lead to loss of power in genetic association tests. Also, repeated measurements of phenotype and dynamic covariates from longitudinal studies bring in more opportunities but also challenges in the discovery of disease-related genetic factors. This dissertation focuses on developing novel statistical methods to address some challenging questions remaining in genetic association studies due to the aforementioned reasons. So far, a lot of methods have been proposed to detect disease-related genetic regions (e.g., genes, pathways). However, with multiple-variant data from a sample with relatedness, it is critical to account for the complex genotypic correlations when assessing genetic contribution. Recognizing the limitations of existing methods, in the first work of this dissertation, the Adaptive-weight Burden Test (ABT) --- a score test between a quantitative trait and the genotype data with complex correlations --- is proposed. ABT achieves higher power by adopting data-driven weights, which make good use of the LD and relatedness. Because the null distribution has been successfully derived, the computational simplicity of ABT makes it a good fit for genome-wide association studies. Genotype missingness commonly arises due to limitations in genotyping technologies. Imputation of the missing values in genotype usually improves quality of the data used in the subsequent association test and thus increases power. Complex correlations, though troublesome, provide the opportunity to proper handling of genotypic missingness. In the second part of this dissertation, a genotype imputation method is developed, which can impute the missingness in multiple genetic variants via the LD and the relatedness. The popularity of longitudinal studies in genetics and genomics calls for methods deliberately designed for repeated measurements. Therefore, a multiple-variant genetic association test for a longitudinal trait on samples with relatedness is developed, which treats the longitudinal measurements as observations of functions and thus takes into account the time factor properly. / PHD / It has been widely recognized that complex diseases are results of poor habits and genetic predisposition. Though people can make their own choices about lifestyle, the mysterious genome language seems to be unchangeable and inevitable. Decoding the messages delivered by DNA can help with prevention, prediction and treatment of diseases. This work focuses on developing novel statistical methods that can make contributions to the detection of disease-related genetic factors. Specifically, given the genotype data and phenotype (e.g., fasting glucose level) data on a sample of individuals where some could be relatives and the rest may be not, three challenges are addressed in this work: (1) how to detect if a genetic region (such as a gene) is significantly associated with the phenotype, while non-genetic information (such as demographic data) is taken into account; (2) how to deal with missing values in genotype data via the relatedness among individuals as well as the similarity among genetic variants; (3) if the phenotype is measured over time for every individual, how to take advantage of the abundant information to discover genes with time-related effects on the phenotype. To address question (1), a hypothesis test is proposed, which is proved being able to successfully detect genes already discovered being associated with a specific trait in previous studies. To address question (2), an imputation method is developed and it is shown that this method can improve the power of association tests. For the third challenge, a second hypothesis test is proposed and it is verified to be able to identify genes contributing to the pattern of a longitudinal trait.

Background: Anorexia nervosa (AN) is a mental disorder characterized by dietary restriction, fear of gaining weight, and distorted body image. Recent studies indicate that the hippocampus, crucial for learning and memory, may be affected in AN, yet subfield-specific effects remain unclear. We investigated hippocampal subfield alterations in acute AN, changes following weight restoration, and their associations with leptin levels. Methods: T1-weighted magnetic resonance imaging scans were processed using FreeSurfer. We compared 22 left and right hemispheric hippocampal subfield volumes cross-sectionally and longitudinally in females with acute AN (n = 165 at baseline, n = 110 after partial weight restoration), healthy female controls (HCs; n = 271), and females after long-term recovery from AN (n = 79) using linear models. Results: We found that most hippocampal subfield volumes were significantly reduced in patients with AN compared with HCs (~−3.9%). Certain areas such as the subiculum exhibited no significant reduction in the acute state of AN, while other areas, such as the hippocampal tail, showed strong decreases (~−9%). Following short-term weight recovery, most subfields increased in volume. Comparisons between participants after long-term weight-recovery and HC yielded no differences. The hippocampal tail volume was positively associated with leptin levels in AN independent of body mass index. Conclusions: Our study provides evidence of differential volumetric differences in hippocampal subfields between individuals with AN and HC and almost complete normalization after weight rehabilitation. These alterations are spatially inhomogeneous and more pronounced compared with other major mental disorders (e.g. major depressive disorder and schizophrenia). We provide novel insights linking hypoleptinemia to hippocampal subfield alterations hinting towards clinical relevance of leptin normalization in AN recovery.

Yes / Objectives: To determine the impact of adherence to spectacle wear on visual acuity (VA) and developing literacy following vision screening at age 4–5 years. Design: Longitudinal study nested within the Born in Bradford birth cohort. Setting and participants: Observation of 944 children: 432 had failed vision screening and were referred (treatment group) and 512 randomly selected (comparison group) who had passed (<0.20 logarithm of the minimum angle of resolution (logMAR) in both eyes). Spectacle wear was observed in school for 2 years following screening and classified as adherent (wearing spectacles at each assessment) or non-adherent. Main outcome measures: Annual measures of VA using a crowded logMAR test. Literacy was measured by Woodcock Reading Mastery Tests-Revised subtest: letter identification. Results: The VA of all children improved with increasing age, −0.009 log units per month (95% CI −0.011 to −0.007) (worse eye). The VA of the adherent group improved significantly more than the comparison group, by an additional −0.008 log units per month (95% CI −0.009 to −0.007) (worse eye) and −0.004 log units per month (95% CI −0.005 to −0.003) in the better eye. Literacy was associated with the VA, letter identification (ID) reduced by −0.9 (95% CI −1.15 to −0.64) for every one line (0.10 logMAR) fall in VA (better eye). This association remained after adjustment for socioeconomic and demographic factors (−0.33, 95% CI −0.54 to −0.12). The adherent group consistently demonstrated higher letter-ID scores compared with the non-adherent group, with the greatest effect size (0.11) in year 3. Conclusions: Early literacy is associated with the level of VA; children who adhere to spectacle wear improve their VA and also have the potential to improve literacy. Our results suggest failure to adhere to spectacle wear has implications for the child’s vision and education. / AB is funded by a National Institute for Health Research Post- Doctoral Fellowship Award (PDF-2013-06-050). The Born in Bradford study presents independent research commissioned by the National Institute for Health Research Collaboration for Applied Health Research and Care (NIHR CLAHRC) and the Programme Grants for Applied Research funding scheme (RP-PG-0407-10044).

Damit Schüler:innen in der Lage sind, an einem zunehmend durch Naturwissenschaften geprägten Alltag teilzuhaben, ist es nötig, dass sie über eine naturwissenschaftliche Grundbildung verfügen. Diese steht in engem Zusammenhang mit einem wissenschaftlich adäquaten Verständnis von Modellen und deren Funktion als Medium zur Kommunikation bereits bekannter Sachverhalte sowie als Methode zur Generierung neuen Wissens. Upmeier zu Belzen und Krüger haben für den Biologieunterricht ein Kompetenzmodell der Modellkompetenz entwickelt, innerhalb dessen zwischen den Teilkompetenzen Eigenschaften von Modellen, Alternative Modelle, Zweck von Modellen, Testen und Ändern von Modellen differenziert wird, die in drei Niveaus graduiert sind. Eine hoch ausgeprägte Modellkompetenz zeichnet sich durch die Fähigkeit aus, über die hypothetischen und erkenntnisgenerierenden Eigenschaften von Modellen zu reflektieren. Für die Förderung einer entsprechenden Modellkompetenz sind Kenntnisse darüber bedeutend, in welchen Niveaus und in welchem Umfang sich die Modellkompetenz von Schüler:innen über mehrere Schuljahre entwickelt. Vor diesem Hintergrund verfolgt die Studie das Ziel, zu untersuchen, inwiefern die im Kompetenzmodell aufgeführten Niveaus eine Entwicklung von Modellkompetenz beschreiben. Dies wurde für die Teilkompetenzen Zweck, Testen und Ändern von Modellen bei zwei Kohorten in einem Längsschnitt von der siebten bis zehnten Jahrgangsstufe bei n = 380 Schüler:innen untersucht. Insgesamt sprechen die Befunde dafür, die im Kompetenzmodell der Modellkompetenz erläuterten Niveaus als Entwicklungsniveaus aufzufassen, die eine Kompetenzentwicklung über mehrere Schuljahre beschreiben und die Veränderung von Kompetenzstrukturen aufzeigen. Für die Klärung der Frage, inwiefern die Niveaus darüber hinaus Stufen darstellen, die im Zuge einer Progression in einer festgelegten Reihenfolge durchlaufen werden, sind weitere Untersuchungen sinnvoll. / In order that high-school level students are able to participate in an everyday life increasingly shaped by science, it is necessary that that they have a certain level of basic scientific literacy. This scientific literacy is closely related to an adequate understanding of models and their function as a medium for communicating already-known facts as well as a means for generating new knowledge. Upmeier zu Belzen and Krüger developed a framework for modeling competence for biology education. They identify five aspects: nature of models, multiple models, purpose of models, testing models, and changing models, each of which is differentiated in three levels. A highly developed modeling competence is characterized by the ability to reflect on the hypothetical character of models and their importance as tools for scientific inquiry. With the intention of fostering an adequate understanding of models and modelling, it is important to gain insight into how students’ abilities develop over time. This study investigates to what extent the theoretical levels of model competence describe different degrees of competence in student learning progression. This is explored for the three aspects purpose of models, testing models, and changing models through a longitudinal study with n = 380 students in grades seven to ten. The findings suggest that the levels of the framework for modeling competence should be regarded as developmental levels that describe a development in student competence over several school years. Yet there is still a research gap regarding the extent to which these levels additionally represent successive levels in a continuous development of competence.

Background: Understanding the factors that contributed to a peaceful and dignified death was essential for improving end-of-life (EoL) care in Canada. Despite ongoing efforts to enhance palliative and hospice services, variations persisted in the quality of death experiences based on location, medical decisions, and personal characteristics. Objectives: This thesis examined the personal and end-of-life factors associated with peace with dying among older adults in Canada. It also explored how location of death and the consideration or receipt of medical assistance in dying (MAiD) influenced the perceived quality of death and dying. Methods: A secondary analysis of data from the Canadian Longitudinal Study on Aging (CLSA) was conducted. The study included next-of-kin interviews of deceased CLSA participants who died between June 2016 and March 2022. Logistic regression was used to assess the association between demographic, clinical, and EoL characteristics and peace with dying. Additionally, the impact of location of death and MAiD on various quality-of-death indicators, including dying with dignity, dying without pain, and dying in one’s preferred place, was examined. Results: Among 3,672 deceased CLSA participants, 1,287 (35.0%) had completed next-of-kin interviews and were included in the analysis. While 66% were reported to have experienced peace with dying, 17% did not. Individuals who were widowed, had an appointed substitute decision-maker, or died of cancer were more likely to experience peace with dying. Those who died at home were more likely to pass away in their preferred location, while individuals in palliative care units or hospices experienced lower levels of pain. Of the decedents, 25.4% had considered MAiD, and 6.7% had received it. Those who considered or received MAiD were more likely to die in their preferred location and experience a positive death process as reported by their next of kin. Conclusion: Nearly one in five older Canadians did not experience peace with dying, highlighting the need to improve EoL care services. While dying at home aligned with individual preferences, hospice and palliative care settings better addressed pain management. MAiD appeared to enhance the quality of dying for those who pursued it. These findings underscored the importance of advanced care planning and patient-centered EoL interventions to ensure dignified and peaceful deaths across care settings in Canada. / Thesis / Doctor of Philosophy (PhD) / The end-of-life experience is a deeply personal journey, yet many older adults in Canada encounter challenges in receiving care that aligns with their preferences. Some individuals wish to pass away at home, while others seek comfort in palliative care or hospice settings. Understanding the factors that contribute to a peaceful and dignified death can help improve end-of-life care across the country. This thesis analyzed data from the Canadian Longitudinal Study on Aging (CLSA) to examine how various factors—such as and personal circumstances, location of death, and medical assistance in dying (MAiD)—shape experiencing peace with dying and overall quality of dying. Using information from next-of-kin interviews, the study assessed the end-of-life experiences of over 1,200 deceased individuals. The findings indicate that while most older adults experience peace with dying, nearly one in five do not. Those who died in their preferred setting, had a substitute decision-maker, or had access to palliative care were more likely to experience a better quality of death. Additionally, individuals who considered or received MAiD were often reported to have a more peaceful end-of-life experience. These insights highlight the importance of improved planning, communication, and access to high-quality palliative and hospice care. By addressing these gaps, healthcare systems can better support individuals and families, ensuring that more Canadians experience a dignified and peaceful death.

Objectives. To investigate diabetes prevalence, incidence, mortality trends, the effects of hyperglycaemia and blood pressure, diabetes and hypertension treatment, and the effect of screening detection on total and cardiovascular disease (CVD), myocardial infarction (MI) and stroke incidence. Study population and methods. Between 1972 and 2001 all patients with diabetes, some detected clinically and some by case-finding procedures (screening), were entered in a diabetes register at Laxå Primary Health Care Center in Sweden. The register included information on medical treatment and laboratory data as well as information on mortality and morbidity from National Registers. The register was supplemented with five non-diabetic subjects, matched to each diabetes patients by age, sex, and year of detection. Results. During the study period 776 new diabetes cases was found, 36 type 1 diabetes mellitus and 740 type 2 diabetes mellitus. Age standardised incidence and prevalence rates for type 1 and type 2 diabetes did not increase over time. Diabetic patients had 17% higher mortality rate than non-diabetic persons, 22% in women and 13% in men. The corresponding over-mortality in CVD was 33%, 41% in women and 27% in men. CVD mortality decreased across time in non-diabetic subjects and in diabetic men but not in diabetic women. Results regarding coronary heart disease (CHD) were similar. CVD incidence increased with fasting blood glucose (FBG), body mass index (BMI), mean arterial blood pressure (MABP), and decreased with metformin treatment and sulfonylurea. Myocardial infarction incidence increased with FBG, BMI and MABP, and decreased with metformin treatment. Stroke incidence increased with MABP. There was no difference in prognoses between those detected by screening or clinically. Conclusions. Diabetes prevalence and incidence did not change over time. The over-mortality according to diabetes was moderate. CVD and MI during follow up were negatively affected by hypertension and hyperglycaemia, and positively by pharmacological diabetic treatment. For stroke no pharmacological protective effect was seen. Screening did not improve prognosis.

Health-related quality of life (HRQL) has become an important outcome in asthma, since traditional outcomes, such as respiratory symptoms and pulmonary function, might not entirely express the patient’s perception of the limitations caused by the disease. The aim of this thesis was to study HRQL in asthma and to analyse if HRQL was related to asthma onset and prognosis. Other aims were to identify determinants of low HRQL in clinically-verified asthmatics, and to study whether low HRQL was a predictor of mortality. In 1990, a self-administered questionnaire was completed by 12,560 individuals from three age groups (16, 30-39, and 60-69 years) in two counties of Sweden. In a second phase, all subjects who reported a history of obstructive respiratory symptoms (n = 1,851) and 600 randomly-selected controls were invited to a clinical investigation including spirometry, allergy testing, and assessment of HRQL with the Gothenburg Quality of Life instrument. In 2003, the eligible subjects in the cohort (n=11,282) were sent a new questionnaire. Mortality data in the cohort was followed up during 1990–2008 using data from the National Board of Health and Welfare Mortality Database. The 616 subjects with clinically-verified asthma 1990 had significantly lower HRQL than subjects without asthma. In the 2003 follow-up, the 305 subjects with persistent asthma had a lower HRQL than the 155 subjects who showed improvement in asthma during the follow-up. Subjects who had developed asthma by the follow-up had a significantly lower HRQL at baseline than those who did not develop asthma. Significant determinants of quality of life in asthma were female sex, smoking habits, higher airway responsiveness to irritants, respiratory symptom severity, positive skin prick test, and absenteeism from work or school. Low HRQL was related to increased mortality, but this association was not found when analyzing the asthmatic group alone. In conclusion, measurements of HRQL are of value for evaluating both the impact and progression of asthma. / <p>medicine doktorsexamen</p>

This thesis explores cultural differences on interactive design features used in websites of South Korea and the United Kingdom from the perspective of both: professional website designers and end-users. It also investigates how the use of interactive design features from different cultures change over time. Four interaction types on websites; User to Interface (U2I), User to Content (U2C), User to Provider (U2P), and User to User (U2U) interactivity, and three interaction types on blogs; Blogger to Interface (B2I), Blogger to Content (B2C) and Blogger to Blogger (B2B) interactivity have been identified. Four cultural dimensions were used for the theoretical base of this study based on which four hypotheses were proposed in relation to the interaction types identified above; (a) High versus Low Context cultures for U2I, (b) High versus Low Uncertainty Avoidance for U2C, (c) High versus Low Power Distance for U2P and (d) Individualism versus Collectivism for U2U interactivity, in order to discover the effects of national cultures on interactivity in websites. We derived our own interactivity dimensions and mapped them to the four interaction types for websites and three for blogs. Interactive design features were derived from interactivity dimensions and examined in our studies. The findings revealed that there have been some changes towards homogeneity in the use of interactive design features on charity websites between South Korea and United Kingdom although there is still evidence of some cultural differences. With regard to end-users’ perspective, the result show that the use of interactive design features of blogs may be influenced by culture but this is only within a certain context. The findings also provide a valuable indication that users interacting within the same blog service can be considered as being shared concerns rather than shared national location, thus create a particular type of community in which bloggers are affected by social influence so they adopt a shared set of value, preferences and style that would indicate almost a common social culture. As a result, the cultural differences derived from their country of origin do not have that much impact.