Robust Model Selection with LARS Based on S-estimators
Bibliographic record
Abstract
We consider the problem of selecting a parsimonious subset of explanatory variables from a potentially large collection of covariates. We are concerned with the case when data quality may be unreliable (e.g. there might be outliers among the observations). When the number of available covariates is moderately large, fitting all possible subsets is not a feasible option. Sequential methods like forward or backward selection are generally “greedy” and may fail to include important predictors when these are correlated. To avoid this problem Efron et al. (2004) proposed the Least Angle Regression algorithm to produce an ordered list of the available covariates (sequencing) according to their relevance. We introduce outlier robust versions of the LARS algorithm based on S-estimators for regression (Rousseeuw and Yohai (1984)). This algorithm is computationally efficient and suitable even when the number of variables exceeds the sample size. Simulation studies show that it is also robust to the presence of outliers in the data and compares favourably to previous proposals in the literature.
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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 | 0.006 | 0.016 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| 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".