Consequences of choosing samples in hypothesis testing to ensure homogeneity of variance
Bibliographic record
Abstract
The two-sample Student t test of location was performed on random samples of scores and on rank-transformed scores from normal and non-normal population distributions with unequal variances. The same test also was performed on scores that had been explicitly selected to have nearly equal sample variances. The desired homogeneity of variance was brought about by repeatedly rejecting pairs of samples having a ratio of standard deviations that exceeded a predetermined cut-off value of 1.1, 1.2, or 1.3, while retaining pairs with ratios less than the cut-off value. Despite this forced conformity with the assumption of equal variances, the tests on the selected samples were no more robust than tests on unselected samples, and in most cases substantially less robust. Under conditions where sample sizes were unequal, so that Type I error rates were inflated and power curves were atypical, the selection procedure produced still greater inflation and distortion of the power curves.
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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 | 0.607 | 0.817 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.004 | 0.004 |
| Bibliometrics | 0.003 | 0.004 |
| Science and technology studies | 0.005 | 0.017 |
| Scholarly communication | 0.004 | 0.006 |
| Open science | 0.005 | 0.006 |
| Research integrity | 0.007 | 0.012 |
| 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; the direct Gemma label and the distilled Codex classifier agree on what is shown here.
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".