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This chapter is about co-evolution of a network with a behavioral variable that is binary and can only go up, not down. Such data structures occur, for example, in research about diffusion of innovations and contagion using survival analysis, event history analysis, etc. The model closely resembles the proportional hazards model (or Cox regression) with censored data. What characterizes the treatment in this book is the assumption that the network on which the behavior depends changes endogenously, partly in response to changes in the behavior. The model differs from the preceding chapters because the effects are now in the rate function rather than the evaluation function.
This chapter probes whether the theory travels beyond Tunisia by conducting a cross-national analysis of grand coalition governments across all democratic transitions between 1942 and 2020. It shows that grand coalitions are statistically associated with democratic collapse, even when controlling for the underlying structural challenges that lead to them. The correlation between grand coalitions and democratic breakdown likewise remains even when pursuing techniques to address potential confounding, such as propensity score matching, inverse probability weighting, and an instrumental variable. The data also lend support for both mechanisms, showing that grand coalitions lead to a higher vote share for populists in the next elections and lead to increased mass polarization as well. While grand coalitions in the first few years of a transition have only mixed effects on democratic breakdown, continuing a coalition beyond that point makes breakdown far more likely. After establishing the rules of the game, new democracies must transition to the politics of competition, rather than continued consensus.
In 2025, a nationwide shortage of long-acting injectable olanzapine (Zypadhera) forced treatment changes in patients at the Mental Health Day Hospital of Mataró (Spain). We retrospectively identified 23 consecutive patients receiving Zypadhera and recorded subsequent therapeutic alternatives, relapse, service disengagement and re-initiation of Zypadhera. Relapse or disengagement occurred in 39% of patients, with significantly fewer events observed among patients switched to oral olanzapine compared with long-acting injectable aripiprazole (log-rank P = 0.008). Female sex, younger age and tobacco use were associated with increased risk. This study highlights the need for contingency planning and careful selection of alternatives.
Autocratization typically results from measures aiming at seizing, strengthening, and consolidating political power. However, it is not without risks: it may produce adverse reactions from multiple actors and possibly lead to the fall of its perpetrators from power. What makes autocratizing incumbents more capable of surviving during such a perilous process? We argue that the adoption of ideological legitimation strategies makes incumbents more capable of surviving during autocratization in democratic and electoral authoritarian regimes. We test our argument through survival analysis of incumbents in power during processes of autocratization from 1900 to 2024. Though relatively understudied in the context of autocratization, our study highlights ideology as a key factor in the process of transformation of a political regime toward autocracy.
This chapter explains analytic or inferential statistics, which extend beyond description to draw conclusions about populations based on sample data. Core concepts such as probability, sampling, hypothesis testing, and confidence intervals are introduced, providing the framework for statistical inference. Common statistical tests, including t-tests, chi-square tests, and regression models, are explained with guidance on their assumptions and appropriate use. The distinction between statistical and clinical significance is emphasised, encouraging cautious interpretation of p-values and consideration of effect sizes. The chapter also addresses issues such as multiple testing, type I and type II errors, and the role of power and sample size in study design. Practical examples illustrate the application of inferential statistics in evaluating treatment effects, identifying risk factors, and testing public health hypotheses. Strengths of inferential methods include their ability to generalise findings, while limitations include vulnerability to misuse and misinterpretation if assumptions are violated. The chapter concludes by underscoring the importance of combining statistical expertise with substantive knowledge. This chapter maps to syllabus sections 2.3–2.6, which cover hypothesis testing, probability, regression, confidence intervals, and the interpretation of p-values.
Individual patient data meta-analyses (IPDMAs) provide powerful tools for synthesizing evidence across studies, yet methods for addressing unmeasured confounding in observational IPDMAs with survival outcomes are rarely implemented. Instrumental variable (IV) approaches offer causal inference capabilities but face practical challenges in hierarchical data structures, particularly the lack of standard diagnostics for instrument strength in nonlinear mixed-effects models. We adapt and evaluate a frequentist mixed-effects two-stage residual inclusion (2SRI) framework for survival IPDMAs, extending traditional IV methods to accommodate study-level and temporal clustering while handling time-to-event outcomes through Cox proportional hazards models. Because classical F-statistics are unavailable for logistic mixed-effects first-stage models, we propose the Wald $\chi ^2$ statistic as a practical instrument-strength diagnostic and empirically characterize its relationship to estimator performance. Through a comprehensive simulation study with 48 scenarios—varying unmeasured confounding (weak to very strong), instrument–treatment association strength (0.3–1.0), and cross-study IV allocation patterns—we evaluated 2SRI against naive mixed-effects Cox models using bias, coverage, variance, and mean squared error. The design was anchored to realistic IPDMA structure (10 studies, $N \approx 4,357$) from pooled Ebola data, with 1,000 replications per scenario. Results show that under weak confounding, naive models dominate on all metrics. With moderate-to-strong confounding and realized Wald $\chi ^2$ exceeding 150–200, mixed-effects 2SRI substantially reduces bias and achieves near-nominal coverage, though with inflated variance. We provide empirical guideposts linking realized first-stage strength to expected performance, enabling analysts to judge when 2SRI will outperform conventional approaches in hierarchical survival IPDMAs. All simulations assume a common treatment effect across studies. Performance under heterogeneous effects remains to be established.
To determine whether sex independently predicts survival in oropharyngeal squamous cell carcinoma and whether human papillomavirus status mediates apparent sex-related survival differences at the population level.
Methods
Population-based cohort study using the Surveillance, Epidemiology, and End Results (SEER) database (17 Registries, 2018–2021). Multivariable Cox regression and a formal sex–human papillomavirus interaction test (likelihood ratio test) were performed in 19,716 patients with known p16/HPV status.
Results
p16-positive disease was more prevalent in males (73.6 per cent vs. 56.2 per cent; p < 0.001). Within human papillomavirus subgroups, survival did not differ significantly between sexes (all p > 0.30). After full adjustment, female sex was not independently associated with overall survival (hazard ratio 0.98; 95 per cent confidence interval 0.91–1.05; p = 0.52) or disease-specific survival (hazard ratio 1.01; p = 0.80). The sex–human papillomavirus interaction was non-significant (hazard ratio 1.057; p = 0.459), confirming human papillomavirus status fully mediates the apparent female survival disadvantage.
Conclusion
Sex is not an independent prognostic variable in oropharyngeal squamous cell carcinoma. HPV/p16-based stratification remains the primary prognostic framework.
Chronotype reflects individual variation in circadian rhythm (CR) (e.g., morningness versus eveningness). CR and chronotype have been associated with dementia pathology, and recent literature suggests that impaired sleep quality and CR disturbances may represent relevant causal factors for dementia. Current evidence is scarce and consists of just a small number of cross-sectional analyses and one longitudinal study. The aim of this study is to investigate the longitudinal association between chronotype and dementia risk in the older adult population, aged 60 years and older.
Methods
Linking data from the Lifelines Cohort Study and data from Vektis obtained by Statistics Netherlands led to a sample for analysis of n = 16,757 participants. Chronotype was measured with the Munich ChronoType Questionnaire (MCTQ) between 2011 and 2015. Chronotype was categorised into five categories: extremely early, slightly early, intermediate, slightly late, extremely late. Dementia incidence was based on having at least one dementia indicator from the Vektis dataset in the years 2018 until 2024. A discrete-time survival model was used to examine the association between chronotype and dementia. Age was specified as the underlying time scale in the discrete-time logistic survival analysis. Sex was included as a covariate. Interactions between age, sex, and educational attainment and chronotype were measured by including relevant interaction terms in the model.
Results
The median age in the sample was 65 years old, and 54% was female. In total, 7% got dementia during a mean follow-up period of 6.6 years. Most individuals had an intermediate chronotype (56%), with about 20% of the individuals having a slightly early and late chronotype, and only about 3% having an extremely early and late chronotype. Individuals with a slightly early (HR, 1.26 [95% CI: 1.08, 1.46]) and an extremely late chronotype (HR, 1.42 [95% CI: 1.00, 2.02]) had an elevated risk of dementia. There were no significant interactions.
Conclusions
Having a slightly early as well as an extremely late chronotype was associated with an elevated risk of dementia.
To analyse the clinical characteristics, treatment and outcomes of minor salivary gland tumours of the upper aerodigestive tract.
Methods
A retrospective study was conducted of patients treated for minor salivary gland tumours between 1988 and 2020. Clinical, pathological and treatment variables were analysed. Survival outcomes were assessed using the Kaplan–Meier method.
Results
Seventy-three patients were included, of which 64 (87.7 per cent) had malignant tumours. The most common histological type was adenoid cystic carcinoma (46.9 per cent), followed by mucoepidermoid carcinoma (32.8 per cent). The oropharynx was the most frequent tumour site. Treatment consisted mainly of surgery with or without adjuvant radiotherapy. During follow up, 28.1 per cent of patients developed local recurrence and 32.8 per cent developed distant metastases. Five- and 10-year disease-specific survival rates were 77.0 and 50.8 per cent, respectively. Advanced stage, tumour location and histological grade were associated with survival.
Conclusion
Minor salivary gland tumours are predominantly malignant and show heterogeneous behaviour. Prognosis is mainly determined by tumour stage, location and histological grade, supporting the need for long-term follow up.
It is difficult to understand the safety profile of drugs based on a single clinical trial since clinical trials are often designed to prove efficacies, and sample size is not powered for safety assessment. Thus, meta-analysis would be a valuable tool to infer the safety profiles utilizing multiple studies. Individual clinical trials usually report the incidence proportions of adverse events (AEs) observed in the study. The follow-up duration may be study-specific, and furthermore different between the treatment groups within a single study. It often occurs in oncology clinical trials and if this is the case, it is hard to interpret the aggregated relative risk of AEs and compare the risk of AEs between the treatment groups with the standard meta-analysis techniques. The progression-free survival or the overall survival is often used as the primary endpoint in oncology clinical trials and the Kaplan–Meier estimates of the survival functions for the primary endpoint are often demonstrated graphically, which give us information of the follow-up duration of the AEs. We propose novel meta-analysis methods for AEs that address differences in follow-up durations by efficiently utilizing the Kaplan–Meier estimates of the primary endpoint. We adapt our approach using both simulated data and real data from a meta-analysis of bevacizumab. Simulation studies demonstrate that the proposed methods perform well when follow-up time differs between trials and groups.
This study aims to provide an updated systematic review on the clinicopathological features, treatment modalities and survival outcomes on SMARCB1-deficient sinonasal carcinoma.
Methods
Five databases were searched: PubMed, Cochrane, Embase, Web of Science and Scopus. Extracted information include demographic data, clinicopathological characteristics and survival outcomes.
Results
A total of 70 studies were included making up a total of 372 patients. Univariable and multivariable analysis performed for prognostic factors of SDSC showed that N+ disease was a statistically significant poor prognostic factor for overall survival, while surgical treatment was a favourable prognostic factor. Treatment with surgery combined with chemotherapy and/or radiotherapy conferred significantly better prognosis compared to chemotherapy or radiotherapy alone.
Conclusion
Our study suggests that N+ disease and isolated treatment with radiotherapy or chemotherapy alone are significant poor prognostic factors for SMARCB1-deficient sinonasal carcinoma, while patients who undergo surgical treatment have significantly better prognosis.
This paper introduces a novel expectation-maximization (EM) algorithm for estimating general phase-type (PH) distributions from left-truncated and right-censored (LTRC) data, a common challenge in survival analysis. The proposed algorithm is highly efficient with computational complexity that scales with the number of nonzero elements in the generator matrix. This feature makes the estimation of high-dimensional, sparse PH models computationally tractable and enables the practical use of the computationally intensive extended information criterion for model selection. Numerical experiments demonstrate its significant speed advantage over a modern benchmark and the applicability of PH models to complex lifetime data.
Late-life depression (LLD) is associated with cognitive impairment and an elevated risk of dementia, yet the influence of age at depression onset on cognitive prognosis remains unclear. Emerging evidence suggests that late-onset depression, defined as first depressive episode in later adulthood, may reflect distinct neuropathological mechanisms and predict more severe cognitive decline and greater dementia risk than early-onset depression.
Aims
This study aimed to investigate whether late-onset depression is linked to domain-specific cognitive impairment and higher risk of incident dementia among older adults with major depressive disorder.
Method
We analysed UK Biobank data from older adults (aged ≥60 years) with primary care linkage, classifying participants into depression-free controls, early-life depression, late-life depression with early onset (LLD-EO) and late-life depression with late onset (LLD-LO). Cognitive performance across these five domains was assessed cross-sectionally at baseline using touchscreen tasks. Incident dementia was evaluated prospectively using clinical records up to 2022. Multi-level models with inverse-probability weighting and survey-adjusted mixed modelling were applied to assess group differences in cognitive function, controlling for demographic covariates, lifestyle factors and physical and mental health conditions. A Cox regression model was employed to estimate dementia risk among groups.
Results
Among 75 064 participants aged ≥60 years, the LLD-LO group (n = 4858) showed significantly worse cognitive performance than healthy controls, particularly on fluid intelligence and visuospatial memory. The LLD-LO group performed worse than LLD-EO on fluid intelligence. During follow-up, LLD-LO was associated with a higher risk of incident dementia (hazard ratio 1.42–1.52) across all adjusted models. Deficits in fluid intelligence and visuospatial memory partially mediated the link between LLD-LO and subsequent dementia.
Conclusions
Late-onset depression showed more severe impairment in fluid intelligence compared with LLD-EO. Late-onset depression was associated with increased incident dementia compared with depression-free individuals.
Although often associated with ageing, disability is becoming increasingly prevalent among young adults. While disability can pose a substantial psychological burden for young adults on critical pathways to establish the foundations for their future, the mental health risks faced by this population remain underexplored.
Aims
This study aimed to (1) assess the association between disability – including its presence, severity and type – and the risk of depressive and anxiety disorders, and (2) examine whether this association varies across sociodemographic factors, health behaviours and comorbidities in a young adult population.
Methods
We conducted a population-based cohort study using linked data from the National Disability Registry and the National Health Insurance Database of South Korea. A total of 6,058,290 individuals aged 20–39 years who underwent health check-ups between 2009 and 2012 were followed through 2022. Cox proportional hazards models were used to estimate adjusted hazard ratios (aHRs) for depressive and anxiety disorders.
Results
Individuals with disabilities had significantly higher risks of depressive (aHR: 1.58, 95% CI: 1.55–1.60) and anxiety disorders (aHR: 1.50, 95% CI: 1.42–1.59). Increased risks were consistently observed across various disability types with the highest risk observed for mental health-related disabilities in depression (aHR: 4.98, 95% CI 4.62–5.37) and epilepsy-related disabilities in anxiety disorders (aHR: 12.05, 95% CI 8.73–16.63). Subgroup analyses revealed stronger associations among individuals in their 20s, low-income groups, non-smokers and those abstaining from alcohol, compared to their respective counterparts.
Conclusions
Young adults with disabilities, a population that has been relatively overlooked in policy discussions, warrant greater policy attention in relation to their mental health.
In this article, the effects of regional autocratic linkage on the survival of autocratic regimes are analysed. Scholars have suggested that regional factors shape regime survival through processes of diffusion. However, in most accounts, diffusion is simply derived from characteristics of the region, such as the number or proportion of regional autocracies. In contrast, it is argued here that it is the actual linkages between countries that must be examined. Regional political, economic and social ties between autocratic regimes create domestic and external stakes in the regime, counterweigh democratisation pressure and facilitate autocratic learning. The study employs the average volume of trade, migration and diplomatic exchanges between autocratic regimes within a region as proxies for regional autocratic linkage, and asserts that regional autocratic linkage is on the rise. Applying Cox survival models on a dataset of regional autocratic linkage and regime survival between 1946 and 2009, it is found that regional autocratic linkage significantly reduces the likelihood of autocratic regime breakdown. These effects hold when the proportion of autocratic regimes within a region is controlled for, suggesting that one must look beyond the characteristics of the countries within a region and focus on the ties and linkages between them.
The objective of this article is to contribute to an understanding of the evolution of a population of social economy enterprises faced with the economic crisis, namely by referring to the case of Montreal. We apply a two-step approach. For one, we use an innovative discrete-time survival model that takes spatial heterogeneity into account. In a second step, this model is used to predict the survival of different forms of the social economy, according to various proposed typologies for identifying hybrid organizational forms. It is understood that certain organizational forms (professional social economy) have fared better than others (emerging social economy). Organizations combining several sources of financing and several forms of paid or volunteer work likewise have greater chances of survival.
The timing of labour market exit differs among socio-economic groups, but the differences by employment history type are not yet well understood. Taking a lifecourse perspective, this study examines to what extent employment patterns from early to mid career are associated with the timing of labour market exit in Belgium. It uses retrospective data from Wave 7 of the Survey of Health, Ageing and Retirement in Europe (SHARE) and applies sequence analysis and cluster analysis to identify five employment history types among 2,417 Belgian respondents aged 50–70: three characterised by continuous full-time work and differing with regard to their timing of labour market entry; the fourth characterised by continuous part-time work; and the fifth, considered the most vulnerable, characterised by discontinuous work. The study applies discrete-time survival analysis to estimate to what extent the timing of labour market exit differs by employment history type. Compared to the Discontinuous career-cluster (reference group), individuals in the Late entry, full-time work-cluster had lower odds of exiting the labour market at any age between 50 and 70, while individuals who also worked full-time almost continuously but entered the labour market early or medium-late had higher odds of exiting the labour market. The difference with the Part-time work-cluster is not statistically significant. The findings show substantial diversity in employment histories among Belgian older individuals and that employment history matters for the timing of labour market exit. In the context of changing retirement policies, ignoring the diversity in employment trajectories risks reinforcing existing social inequalities.
Co-optation is one of the most important concepts that have been discussed in recent years to explain the persistence of autocratic regimes. Institutions like parties, legislatures, and elections have all been shown to fulfil a co-optation function. However, a broader assessment of co-optation beyond an institutional focus has yet to be undertaken. This article addresses this lacuna and presents a comprehensive concept and operationalisation of co-optation in autocratic regimes. The article argues that co-optation is constituted by the compensation of the regime’s vulnerability to threats posed by powerful societal pressure groups. The article highlights how compensation of vulnerability can be achieved through institutional inclusion or material benefits, and how this has to be tailored to the respective pressure group’s requirements. I collect twenty-six indicators of vulnerability and compensation related to six societal pressure groups and aggregate them into an index of co-optation that reflects the structure of the theoretical concept. The index is evaluated by examining distributions within and across categories of autocratic legislatures, and by testing its effect on autocratic regime breakdown in a set of Cox survival models.
Timely dissemination of clinical trial results is essential to advance knowledge, guide practice, and improve outcomes, yet many trials remain unpublished, limiting impact. We examine what drives publication and timelines across three major clinical domains.
Methods:
We analyzed study design and factors associated with dissemination of interventional trials, focusing on cardiovascular disease (CVD), cancer, and COVID-19. A total of 10,785 trials (CVD: 5929; cancer: 4210; COVID-19: 646) were linked to PubMed publications using National Clinical Trial identifiers. Study design, operational, and transparency-related features were assessed as predictors of time to publication, defined as the interval from study completion to first publication, using Cox proportional hazards model.
Results:
COVID-19 trials had the highest publication rate (49.6%), followed by CVD (42.3%) and cancer (32.9%), likely reflecting pandemic-related prioritization. Faster publication was associated with larger enrollment, more sites, result posting, randomization, DMC presence, and higher blinding levels (all p < 0.05). Slower publication was linked to supportive care or diagnostic trials (CVD), basic science (cancer), and later COVID-19 trial completion. In subgroups, U.S. facility presence (CVD) and phase 3 design (cancer) predicted faster publication, while healthy volunteer inclusion (CVD) predicted slower publication. Among DMC trials, more secondary outcomes were linked to faster publication across all disease areas.
Conclusions:
Key study design and operational factors consistently predict whether and when trials are published. Strengthening methodological rigor, result reporting, and multi-site collaboration may accelerate timely dissemination into peer-reviewed literature.
In this study, we investigate the impact of the age of prime ministers and ministers on the stability of governments across 21 democracies. We examine this issue by using Cox survival analysis, leveraging an original dataset and adopting a comparative perspective. The findings of the study document that younger prime ministers face a lower risk of government discretionary termination compared to their older counterparts. This effect does not appear to be statistically significant for cabinet ministers. By shedding light on this uncharted relationship, we contribute to the flourishing literature on youth representation in politics and the established research agenda on the factors affecting the survival in office of democratic governments. We conclude the study by discussing the implications of the findings for democracy and suggesting avenues for future research.