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Understanding similarity scores

How to read Turnitin Similarity results and decide what actually needs revision.

SimilarityWritingReports

A score is a signal, not a verdict

A Similarity percentage tells you how much text overlaps with known sources. It does not automatically prove plagiarism, and a low score does not guarantee perfect originality.

The useful work is in the highlighted passages: quotations, bibliography, common methods language, copied explanations, and poorly paraphrased source text need different decisions.

What to review first

  • Long highlighted blocks from one source
  • Unquoted sentences that preserve another author’s structure
  • Repeated matches in argument or analysis sections
  • References and boilerplate that should be excluded from judgment

How AI reports fit in

AI detection and Similarity answer different questions. A passage can be original but machine-like, or copied from a web page without looking AI-generated.

Review both reports together and revise for authorship, citation quality, and clarity instead of chasing a single magic number.