The DataLens Africa Blog

Your Guide to Africa's AI Data Landscape

Discover how Africa is closing the AI data gap. Read our latest insights on data annotation, localized language models, and the ethical infrastructure driving the continent's digital future.

The kappa formula beside a grid of annotators labeling items, with disagreement rows highlighted
Data Ethics

Data Labeling Quality Metrics: IAA, Cohen's Kappa & Fleiss' Kappa Explained

"Our annotators agree 90% of the time" sounds like a quality guarantee. It often isn't. How inter-annotator agreement, Cohen's kappa, and Fleiss' kappa really measure label quality, and why, on subjective African-language tasks, disagreement can be the most important signal in your dataset.

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