Investigation into the claim of weighted Cusum in authorship attribution studies

Abstract

Although there has been detailed criticism of the Cusum technique for authorship attribution the claims of its proponents are so attractive to the legal profession that any suggestion that the technique can be 'improved' requires careful consideration. One such suggestion is that the arbitrary nature of the judgements made of Cusum charts can be removed by 'weighting' the calculations of the Cusum values. To test the claims of weighted Cusums three texts from seven different authors were subjected to the weighted Cusum analysis; each of the three groups consisted of twenty-one samples. The results obtained in this experiment showed that only three out of sixty-three texts were identified as being written by more than one author. However, these three texts were derived from single-authored material. Further, none of the twenty-one multiple-authored texts produced significant results that would have led to the identification of more than one author. Therefore, the weighted Cusum technique did not reliably discriminate between texts of single and multiple authors.