Inverse-intensity weighted generalized estimating equations for longitudinal data subject to irregular observation: which variables should be included in the visit rate model?
Bibliographic record
Abstract
Longitudinal data are often subject to irregular and informative visit times. Weighting generalized estimating equations by the inverse of the visit rate yields asymptotically unbiased estimates of regression coefficients provided that outcomes and visit times are conditionally independent, given the covariates in the visit model. Adding other covariates has no impact on the asymptotic bias of estimated regression coefficients, provided that conditional independence is maintained, but the impact on their variances is unknown. We show that variances are unchanged on adding variables associated with neither outcome nor visit process, and decrease on adding variables associated with outcome but not visit process. Adding variables associated with visits but not outcome may either increase or decrease variances of estimated outcome model regression coefficients, depending on the correlation structure of the covariates and the outcome. Application to a study of major depressive disorder found that the variances of estimated regression coefficients were of a similar magnitude when predictors of outcome but not visits were added to the visit rate model but consistently larger, in some cases by a factor of 2, on adding predictors of visits but not outcome. We recommend that visit process models include variables associated with outcome, but that those unassociated with the outcome be treated with caution.
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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 | 0.041 | 0.164 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.003 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.004 |
| Open science | 0.004 | 0.002 |
| Research integrity | 0.002 | 0.004 |
| Insufficient payload (model declined to judge) | 0.003 | 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".