Skip to Main Content
Caltech Library logo

Ithenticate at Caltech: Understanding Similarity Reports and Indexes

The Similarity Report and the Similarity Index

Similarity Report

The Similarity Report provides an overall similarity breakdown for each submission to the iThenticate database. This breakdown determines the percentage of similarity between a submission and content existing in the database of the text comparison tool, iThenticate.

  • Accessing the Similarity Report
  • The Document Viewer can be viewed in four different modes. These modes allow you to view and sort the information contained in the Similarity Report to best suit your needs. The four modes for viewing a Similarity Report are:
    • Match Overview: (show highest matches together): A list of all areas of the paper which have similarity to information in the selected search repositories
    • All Sources: Allows a user to view matches between the paper and a specifically selected source in the content repositories. 
    • Match Breakdown: Displays matches that are obscured by a top source. 
    • Side By Side Comparison: An in depth view that shows a document’s match compared side by side with the original source content from the content repositories.
  • You may also view the Similarity Report in a Text-Only Report format.
    • You can navigate to the text only report by clicking on the Text-Only Report button at the bottom right of the document viewer.
    • The text only report allows you to view the Similarity Report without the document formatting. The view is separated into three main areas in the default view.
      • The default viewing mode is the Similarity Report. This mode has a similar layout to the Document Viewer.
      • Content Tracking mode lists all the matches between the databases and the submitted document.
      • The Summary Report mode offers a simple, printable list of the matches found followed by the paper with the matching areas highlighted. It shows the sources first, with the document text below.
  • The Similarity Report can be downloaded in a print-friendly PDF.

Similarity Index

The Similarity Index is one component of the report iThenticate provides after analyzing a submitted document and comparing it with other documents in its database. The Similarity Index numerically rates the similarity of the submitted text by percentages. 

The Index is also another name for the Similarity Score.  The similarity score is the percentage that your paper matches with other sources on the Turnitin database. The proportion of the similarity score is denoted by color.

Interpreting the Similarity Report

Interpreting the Similarity Report must be done with care.  A high score can mean there is no problem; a low score may not mean there is no problem.

iThenticate does not check for plagiarism in a submission. It checks a submission against the content database, and if there are instances where the submission's content is similar to, or matches against, one or more sources, it will be flagged for review. The database includes billions of web pages (both current and archived content), a repository of work that has been submitted to Turnitin in the past, a collection of documents, which comprises of thousands of periodicals, journals, publications, and CrossRef member content.

It is perfectly natural for a submission to match against sources in the database. If the submission has used quotes and has referenced correctly, there will be instances where there will be a match. The similarity score simply makes the user aware of any problem areas in the submission; iThenticate should be used as part of a larger process, in order to determine if the match is or is not acceptable.

Filters and Exclusions

To view the Filters & Settings menu, select the filters icon at the bottom of the Document Viewer sidebar.


You may:

  • Exclude Quoted or Bibliographic Material
  • Exclude Small Sources
  • Exclude Small Matches
  • Exclude Sections
  • Exclude a Match