Why are plagiarism scores in Turnitin Ouriginality Check higher than in Ouriginal?

Since switching to Turnitin Ouriginality Check, it has become noticeable that similarity percentages are often higher than before in Ouriginal. This does not mean that students suddenly plagiarise more; it is mainly due to differences in the way detection and calculation are performed.

Key differences

• Improved detection through more advanced technology
  Because Turnitin detects more precisely than Ouriginal, overlap is found more often, and the percentage can be higher. This is not a cause for concern — it simply indicates that more text has been recognised.

• Larger database
  Turnitin compares submissions against a much broader set of sources, including millions of previously submitted student papers, academic publications and commercial databases. This results in more frequent overlap detection.

• Different calculation method
  Where Ouriginal ignored certain short or commonly used fragments, Turnitin includes them more often. Paraphrases, quotes and reference lists can also count as overlap.
  Instructors can partly control this using filters (see below).

How to interpret the score

• See the percentage as a starting point, not as a final conclusion.

• Look at the content of the overlap: quotes, reference lists and standard formulations are often included but are usually harmless.

• Use filters in Turnitin to get a more realistic view.

What can I configure as an instructor?

Instructors can refine the report using filters. This can be done at two points:

1. Beforehand – when creating the assignment in Brightspace

• Create a Turnitin assignment.

• Open Manage Turnitin and go to More Options.

• Here you can configure:

  • Exclude Bibliography – exclude the bibliography.

  • Exclude Quotes – exclude quotes.

  • Exclude Small Matches – exclude small matches (set a minimum number of words or percentage).

• These settings apply to all submissions within that assignment.

2. Afterwards – in the individual Similarity Report

• • Open a submitted document by clicking the red percentage.

  • Open the filter panel (funnel icon).

• There you can apply the same options:

  • Exclude Bibliography

  • Exclude Quotes

  • Exclude Small Matches – exclude small matches (set a minimum number of words or percentage)

• After applying the filter, the score is recalculated immediately, allowing you to compare the raw score with the filtered score.

Useful links to explanations of the Similarity Score:

Understanding the Similarity Score:

https://guides.turnitin.com/hc/nl/articles/23435833938701