Burstiness
Definition
The variance in sentence-level complexity across a passage. Human writing tends to mix complex and simple sentences unevenly; LLM output tends to be more uniform. Some detection tools use burstiness as a discriminating feature, though its reliability is contested.
- Measures
- Variance in sentence complexity across a passage
- Human writing
- Tends toward uneven, mixed complexity
- LLM output
- Tends toward more uniform complexity
- Reliability
- Contested as a standalone detection signal
Common questions
Why is burstiness treated as a contested signal rather than a reliable test?+
Prompted or edited LLM text can be made more varied, and some human writers produce naturally uniform prose, so burstiness alone produces false positives and false negatives. Detection tools generally combine it with other statistical and linguistic features rather than relying on it in isolation.
How does burstiness differ from perplexity in AI-text detection?+
Perplexity measures how predictable individual word choices are to a language model, while burstiness measures the variation in sentence-level complexity across the whole passage. The two capture different aspects of style and are often used together.
Related terms
- AI Detection Classifier
- A machine-learning system trained to discriminate between human-written and LLM-generated text by measuring features such as perplexity, burstiness, and n-gram probabilities. Current...
- Human-LLM Collaboration
- Text production in which a human contributes prompts, editing decisions, and intentional content while an LLM generates or transforms the prose. The...
- Large Language Model (LLM)
- A neural network trained on large text corpora to predict likely next tokens. At inference, it generates text by sampling from probability...
- Perplexity
- A measure of how surprising a sequence of words is to a language model. LLMs tend to generate low-perplexity text (predictable word...
- Stylometric Signature
- The set of measurable linguistic features : function-word frequencies, sentence length, punctuation patterns, vocabulary richness : that characterises a specific writer's output...