Inter-rater Reliability of the Classification of the J-Sign Is Inadequate Among Experts
Bibliographic record
Abstract
OBJECTIVE: The purpose of this study was to determine the inter-rater and intra-rater reliability of the symmetry, classification, and underlying pathoanatomy associated with the J-sign in patients with recurrent lateral patellofemoral instability. STUDY DESIGN: Blinded, inter-rater reliability study. SETTING: N/A. PARTICIPANTS: Thirty patellofemoral joint experts. INTERVENTIONS: Thirty clinicians independently assessed 30 video recordings of patients with recurrent lateral patellofemoral instability performing the J-sign test. MAIN OUTCOME MEASURES: Raters documented J-sign symmetry and graded it according to the quadrant and Donell classifications. Raters indicated the most significant underlying pathoanatomy and presence of sagittal plane maltracking. Intra-rater reliability was assessed by 4 raters repeating the assessments. Mean pairwise simple and/or weighted Cohen's kappa were performed to measure inter-rater and intra-rater reliability, as well as calculation of percent agreement. RESULTS: J-sign symmetry demonstrated fair inter-rater reliability (k = 0.26), whereas intra-rater reliability was moderate (k = 0.48). Inter-rater reliability for the quadrant and Donell classifications indicated moderate agreement, k = 0.51 and k = 0.49, respectively, whereas intra-rater reliability was k = 0.79 and k = 0.72, indicating substantial agreement. Inter-rater reliability of the foremost underlying pathoanatomy produced only slight agreement (k = 0.20); however, intra-rater reliability was substantial (k = 0.68). Sagittal plane maltracking demonstrated slight inter-rater agreement (k = 0.23) but substantial intra-rater agreement (k = 0.64). CONCLUSIONS: The symmetry, classification, and underlying pathoanatomy of the J-sign demonstrated fair to moderate inter-rater reliability and moderate to substantial intra-rater reliability among expert reviewers using video recordings of patients with recurrent lateral patellofemoral instability. These findings suggest individual raters have a consistent standard for assessing the J-sign, but that these standards are not reliable between assessors. LEVEL OF EVIDENCE: III.
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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 | 0.150 | 0.251 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.003 |
| Research integrity | 0.001 | 0.001 |
| 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".