To refine your similarity scores, consider the following Similarity Report filters:
Exclude small sources (measured by word number of percentage)
You can exclude sources in the source list that are below the threshold set by you. For example, if the threshold is set at 3%, any 1% or 2% match would be removed from the current report mode's source list (Match Overview or All Sources).
Exclude quotes and bibliography
Quotes and bibliography items are widely reused and generally fail to demonstrate original writing. You may wish to exclude quotes, bibliographies, and items of a similar nature from influencing your students' similarity scores.
Generate a new Similarity Report
If you believe an item may have been added to the Turnitin database since a Similarity Report was last generated (this could be a website, journal article, or even another student’s paper), you can generate a new report to receive an up-to-date score.