When a paper is submitted via Turnitin, an overall percentage of similarity or originality score (with colour code) is shown (see picture below). The similarity score is just a percentage of text in the student’s paper that matches sources in the Turnitin database. Turnitin does not detect nor check for plagiarism but it highlights the text in the student’s paper that is similar to or matches against another source. The picture below shows a Turnitin Originality Report in the Document Viewer window. On the right of the image, you will see a numbered list of matched sources. Each of these is allocated a colour and number and these correspond to the number and colour in the student’s text. A high percentage does not mean there is plagiarism and a low match score does not mean there is no plagiarism. However, a large percentage could indicate that the student has used too much from one source, or a direct copying of text from that source – see the red highlighted text numbered 1. A high percentage could also mean poor paraphrasing by student – see the pink highlighted text numbered 2. Both these high percentages are grounds for further investigation by the teacher on the student’s paper as direct copying and insufficient paraphrasing, even with proper referencing are considered as plagiarism. 

At Wittenborg, up to 20% similarity is acceptable for all submissions through Turnitin as long as the submission is properly referenced as per Harvard referencing style. Above 20% but no more than 30% similarity must be motivated/justified by the student to be accepted for assessment. The 20% similarity does not automatically imply the submission is plagiarism-free as there could also be cases of plagiarism with less than 20% similarity. The submission must be properly referenced as per Harvard referencing style.

Source: www.wittenborg-online.com