What causes false positives in AI detectors?

Base rate fallacy —low AI use means most flags hit human work, even at 95% accuracy.

How accurate are AI text detectors really?

Depends on base rate. At 10% AI use, flagged text is ~68% likely AI; at 1%, just 16%.

Should I trust an AI detector flag on my writing?

Nope—demand posterior probability adjusted for your context's base rate.

AI Detectors' 98% Flag? Dead Wrong for Most—Blame the Math

Picture this: your essay, poured over for weeks, slammed as 98% AI-generated. Heart sinks. But math reveals it's probably yours—thanks to a sneaky probability trap called the base rate fallacy.

theAIcatchup Apr 09, 2026 3 min read

Overlapping bell curves of human vs AI text perplexity distributions

⚡ Key Takeaways

AI detectors' high accuracy claims ignore base rates, leading to 30%+ false positives on flags. 𝕏
Bayes' theorem reveals true odds: a 98% confidence score drops to 72% with 5% base rate. 𝕏
Future fix? Open-source tools with adjustable base rates—democratizing honest detection. 𝕏

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theAIcatchup

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#AI detectors #Bayes theorem #base rate fallacy #false positives

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Originally reported by Dev.to

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