The utility of latent variable models in refining behavioural crime scene analysis of serial stranger sexual offences
Bibliographic record
Abstract
Behavioural crime scene analysis (BCSA) is a police tool used to reconstruct an offence based on behaviours. Recently, BCSA has demonstrated clinical utility by predicting recidivism and aiding case conceptualization. However, a systematic review of BCSA models showed a paucity of research evaluating which behaviours are necessary and sufficient to model sexual offences. Groth and Birnbaum’s sex offender typology, which is based on offence behaviours, provides a theoretical framework that integrates investigative information and clinical practice. The purpose of this thesis was to evaluate statistical- and theory-based approaches to refine BCSA models that distinguish sexual offenders. In Studies 1 through 3, Multidimensional Scaling, Nonlinear Principal Component Analysis, and Latent Class Analysis were used to create statistically-driven and theory-driven behavioural models from 59 serial, stranger sexual offenders. Validity testing of the theory-driven model indicated that applying Groth and Birnbaum’s framework to BCSA could optimize both investigative efforts and clinical decision-making.
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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 | 0.116 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.004 |
| Bibliometrics | 0.008 | 0.006 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.005 | 0.004 |
| Open science | 0.002 | 0.003 |
| Research integrity | 0.001 | 0.004 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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".