ReviewMethodsX2023
Gwet's AC1 is not a substitute for Cohen's kappa - A comparison of basic properties.
Review in MethodsX, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 26 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
26 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Evaluating the effectiveness of substance use disorder treatment centers: a systematic review of international standards and outcomes.Substance abuse treatment, prevention, and policy · 2026Pooled it
- Subjective Xerostomia and Chairside Salivary Dysfunction in Institutionalized Older Adults: Concordance and Exploratory Derivation of a Five-Item Short Form.Dentistry journal · 2026Article
- Assessing Inter-Rater Agreement Across Five Teams Applying the Global Trigger Tool to Review 200 Inpatient Medical Records.Journal of patient safety · 2026Article
- Reliability of Physical Examination Findings in Youths Diagnosed With Pneumonia.JAMA network open · 2026Article
- Article
- Researchers' Mental Health and Quality of Life: A Protocol for Systematic Review and Meta-Analysis.Health science reports · 2026Article
- Assessing observer-dependent dental age estimation procedures: intra- and inter-observer reliability across four well established radiographic systems for dental analysis.International journal of legal medicine · 2026Article
- Agreement testing of AMSTAR-PF, a tool for quality appraisal of systematic reviews of prognostic factor studies.BMJ open · 2026Observational
- Article
- Article
- AI's ability to interpret unlabeled anatomy images and supplement educational research as an AI rater.Anatomical sciences education · 2025Article
- Measuring Agreement in Diagnostics: A Practical Guide for Researchers.Statistics in medicine · 2025Article
- A Framework for Measuring Treatment Fidelity in Motor-Based Speech Intervention for Children With Childhood Apraxia of Speech.American journal of speech-language pathology · 2025Article
- Post-Thoracentesis Ultrasound versus Chest Radiography for the Evaluation of Effusion Evacuation and Lung Reexpansion: A Multicenter Study.Annals of the American Thoracic Society · 2025Article
- Some common statistical methods for assessing rater agreement in radiological studies.Acta radiologica (Stockholm, Sweden : 1987) · 2025Review
- Artificial Intelligence Algorithm to Screen for Diabetic Neuropathy: A Pilot Study.Biomedicines · 2025Article
- There Is Poor Agreement between the Subjective and Quantitative Adjudication of Aneurysm Wall Enhancement.AJNR. American journal of neuroradiology · 2025Article
- Deconstructing rurality to better "place" health data.International journal of geographical information science : IJGIS · 2025Article
- A comparative analysis of INTERGROWTH-21st and the World Health Organisation fetal growth chart in detection of term small for gestational age newborns and prediction of short-term adverse perinatal outcomes.BMJ paediatrics open · 2025Article
- Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
2 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Gwet's AC1 has been proposed as an alternative to Cohen's kappa in evaluating the agreement between two binary ratings. This approach is becoming increasingly popular, and researchers have been criticized for still using Cohen's kappa. However, a rigorous discussion of properties of Gwet's AC1 is still missing. In this paper several basic properties of Gwet's AC1 are investigated and compared with those of Cohen's kappa, in particular the dependence on the prevalence of positive ratings for a given agreement rate and the behaviour in case of no association or maximal disagreement. Both approaches compare the observed agreement rate with a comparative number. Cohen's kappa uses an expected agreement rate as comparator, whereas Gwet's AC1 uses an expected disagreement rate. Consequently, for a fixed agreement rate, Gwet's AC1 increases with increasing difference of the prevalence of positive ratings from 0.5. In contrast, Cohen's kappa decreases. Gwet's AC1 can take positive and negative values in the case of no association between the two raters, whereas Cohen's kappa is 0. Due to these fundamental differences, Gwet's AC1 should not be seen as a substitute for Cohen's kappa. In particular, the verbal classification of kappa values by Landis & Koch should not be applied to Gwet's AC1.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.