Turnitin generates two distinct reports for university submissions: the classic Similarity Index and the newer AI Writing Detection percentage. Knowing how examiners interpret these scores is essential for peace of mind before final submission.
1. What the Similarity Percentage Actually Means
Turnitin compares your text against billions of archived student papers, published journals, and web pages. A 15% similarity score does NOT mean 15% plagiarism. Matches often include:
- Standard references and bibliography items
- Direct quotations enclosed in quotation marks
- Common terminology, statutory titles, and methodological phrases
2. Acceptable Similarity Thresholds
Most UK and Australian universities consider 10% to 20% normal for dissertations once bibliography and quotations are filtered. Examiners investigate individual matched strings rather than the top-line number alone.
3. Turnitin AI Detection Explained
Turnitin's AI detector evaluates statistical patterns in sentence structure and word perplexity. To ensure your authentic academic voice shines through: write in active voice, incorporate unique critical commentary, and cite primary empirical evidence throughout.