Category Archives: 2. Originality Reports

Interpreting the % similarity figure

The most comment questions colleagues ask about the % similarity figure are:-

  • ‘What does the %  figure specify ?’
  • ‘Is there a figure I can use to say which reports need looking at?’

To take these in turn.

The % similarity figure measures how much of the piece of work Turnitin has matched to sources in its database, measured as a percentage of the total number of words in the document. So in a 100 word piece, if 45 words can be matched the report would show a match of 45%, in a 2500 word piece a match of 23% would mean 575 words matched.

This figure says nothing at all about whether these matched words are

  • properly referenced quotations
  • commonly used phrases from the subject/discipline
  • insufficiently or non-referenced text

It is important that somebody looks at the originality report to make a judgement about the matched text.

Because of this, it is impossible to give a similarity figure as a threshold. Two assessments could have the same figure; in once case this could be made of of many small phrases and references which are all totally acceptable; in the other case it could be a complete paragraph or paragraphs without proper attribution. Turnitin cannot distinguish between these two cases.