Impact evaluation of job training programmes: Selection bias in multilevel models
Bibliographic record
Abstract
This paper focuses on the evaluation of a job training programme composed of several different courses. The aim is to evaluate the impact of the programme for the participants with respect to non-participants, paying attention to possible differences in the effectiveness between the courses. The analysis is based on discrete data with a hierarchical structure. Multilevel modelling is the natural choice in this setting, but the results may be severely affected by selection bias. We propose a two-step procedure, which suits both the hierarchical structure and the observational nature of data. The method selects the appropriate control group, using standard results of the propensity score methodology. A suitable multilevel model is formulated, and the dependence of the results on the amount of non-random sample selection is analysed within a likelihood-based framework. As a result, rankings for comparative performances are obtained, adjusted for the amount of plausible selection bias. The procedure is illustrated with reference to a data set about a job training programme organized in Italy in the late 1990s.
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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 | 0.099 | 0.254 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.004 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.002 | 0.004 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 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".