Switched on per assignment
Faculty tick similarity checking on an assignment and run the check from its submissions list. Each hand-in is read as it arrives, so later hand-ins are compared with earlier ones.
File types
PDF files with a text layer, Word .docx, plain text and web pages. A scanned PDF with no text layer is reported as such rather than scored.
How matches are found
Each text is reduced to fingerprints of overlapping six-word sequences, using a technique known as winnowing, and a matched run must be at least ten words long to count. Words in Indian scripts such as Devanagari are read as words, not discarded.
What is not counted
Passages in quotation marks, a closing references list and text taken from the assignment’s own brief. A phrase found across much of the subject’s work is treated as the subject’s common language.
The report
A percentage for each hand-in, with its text shown and matched passages highlighted in a colour per source, each set beside the source passage it matches.
Privacy between classes
A marker sees another student’s words only for classes they teach. A match with a class they do not teach is shown without the name or the text.
Students’ own view
Optionally, a student sees their own percentage and highlighted passages, never whose work they match, and can hand in a corrected file before the due date.
Group work
For group assignments, every member of the group sees the group’s hand-in and its report as their own.
Retention and erasure
The extracted text is covered by the institution’s retention schedule, and a student’s hand-in files, extracted text and fingerprints are removed when their personal data is erased.