Reliability in unidimensional ordinal data: A comparison of continuous and ordinal estimators.
Bibliographic record
Abstract
This study challenges three common methodological beliefs and practices. The first question examines whether ordinal reliability estimators are more accurate than continuous estimators for unidimensional data with uncorrelated errors. Continuous estimators (e.g., coefficient alpha) can be applied to both continuous and ordinal data, while ordinal estimators (e.g., ordinal alpha and categorical omega) are specific to ordinal data. Although ordinal estimators are often argued to have conceptual advantages, comprehensive investigations into their accuracy are limited. The second question explores the relationship between skewness and kurtosis in ordinal data. Previous simulation studies have primarily examined cases where skewness and kurtosis change in the same direction, leaving gaps in understanding their independent effects. The third question addresses item response theory (IRT) models: Should the scaling constant always be fixed at the same value (e.g., 1.7)? To answer these questions, this study conducted a Monte Carlo simulation comparing four continuous estimators and eight ordinal estimators. The results indicated that most estimators achieved acceptable levels of accuracy. On average, ordinal estimators were slightly less accurate than continuous estimators, though the difference was smaller than what most users would consider practically significant (e.g., less than 0.01). However, ordinal alpha stood out as a notable exception, severely overestimating reliability across various conditions. Regarding the scaling constant in IRT models, the results indicated that its optimal value varied depending on the data type (e.g., dichotomous vs. polytomous). In some cases, values below 1.7 were optimal, while in others, values above 1.8 were optimal. (PsycInfo Database Record (c) 2025 APA, all rights reserved).
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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 | 0.307 | 0.655 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.002 |
| Bibliometrics | 0.010 | 0.014 |
| Science and technology studies | 0.002 | 0.009 |
| Scholarly communication | 0.007 | 0.009 |
| Open science | 0.003 | 0.007 |
| Research integrity | 0.002 | 0.005 |
| 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".