1A statistical procedure for identifying changes in the probability distribution of a given process by considering cumulative sums associated with that process; a cumulative sum used in this procedure. Usually attributive, as "cusum chart", "cusum test", etc.
The procedure was first developed by E. S. Page in 1954. It is most commonly used in quality control and in the monitoring of industrial processes.
2A method for analysing the authorship of texts by considering cumulative sums which chart the frequencies of a particular stylistic feature (especially sentence length) throughout a given text.
This method of analysis was proposed by Andrew Queen Morton in 1967. Although previously accepted as evidence in trials in the United Kingdom, its validity and reliability has often been called into question.
1960s; earliest use found in Quality Control & Applied Statistics. Acronym from the initial letters of cumulative sum.