A unified joint modelling of zero-inflated longitudinal measurements and time-to-event outcomes with applications to HIV and colorectal cancer data
Bibliographic record
Abstract
In this manuscript, we develop a unified joint modelling and estimation framework for zero-inflated count and longitudinal semi-continuous data, with a focus on models structured around the exponential family and two-part hurdle formulations. We first review and synthesize existing longitudinal hurdle models, identifying a common structure across diverse approaches. Motivated by this foundation, we introduce novel joint models that integrate semi-continuous longitudinal outcomes with time-to-event data, and propose new methods for dynamic prediction in the presence of semi-continuous outcomes. To facilitate flexible estimation and inference across this class of models, we propose a Bayesian estimation strategy based on a Markov Chain Monte Carlo (MCMC) algorithm. We have implemented these methods in the R package UHJM (available at https://github.com/tbaghfalaki/UHJM), providing accessible tools for parameter estimation and risk prediction. The utility of our framework is demonstrated through simulation studies and two real-world applications characterized by excess zeros.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.025 | 0.059 |
| Meta-epidemiology (narrow) | 0.001 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.003 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.004 |
| Open science | 0.005 | 0.004 |
| Research integrity | 0.003 | 0.004 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".