Response similarity analysis, RSA


Lertap 5 has a cheat-checker referred to as "RSA". It's used to determine if the answers a pair of students gave on a multiple-choice test were exceptionally and unexpectedly similar.

When an RSA analysis is run, Lertap gets Excel to create a variety of tables with descriptive and inferential statistics.



In this example, a real-life case, 384 students sat a 59-item test. RSA indicated that, out of a total of 73,538 pairs of students, 3 student pairs had response patterns which could be regarded as "suspicious". Seating charts from the exam venue indicated that these pairs were seated in close proximity, and thus would have had the chance to share answers. The first pair of students in the table above had only a single response difference over all items (the D column), and gave the same incorrect answer on 25 items (EEIC). RSA's "Sigma" statistic found this to be a very unlikely result by chance alone -- the two students were interviewed, confessed to cheating, and were suspended for one semester.


To read up on RSA, see this paper, this Lelp topic, and the dataset used in this example.