Efficient outlier detection in numerical and categorical data
Bibliographic record
Abstract
Abstract How to spot outliers in a large, unlabeled dataset with both numerical and categorical attributes? How to do it in a fast and scalable way? Outlier detection has many applications; it is covered therefore by an extensive literature. The distance-based detectors are the most popular ones. However, they still have two major drawbacks: (a) the intensive neighborhood search that takes hours or even days to complete in large data, and; (b) the inability to process categorical attributes. This paper tackles both problems by presenting HySortOD : a new, fast and scalable detector for numerical and categorical data. Our main focus is the analysis of datasets with many instances, and a low-to-moderate number of attributes. We studied dozens of real, benchmark datasets with up to one million instances ; HySortOD outperformed nine competitors from the state of the art in runtime, being up to six orders of magnitude faster in large data, while maintaining high accuracy. Finally, we also performed an extensive experimental evaluation that confirms the ability of our method to obtain high-quality results from both real and synthetic datasets with categorical attributes.
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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 | 0.002 | 0.013 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.003 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 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".