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Six words are sufficient !? Mike Child & Fintan Culwin . 3 * 3 * 7 * 2 * 6 * 5 * 5 = 18,900 possible sentences each with a probability of .00005. It is possible by chance alone. “it” is reported by Google to appear in about 850,000,000 documents.
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3 * 3 * 7 * 2 * 6 * 5 * 5 = 18,900 possible sentences each with a probability of .00005
It is possible by chance alone. “it” is reported by Google to appear in about 850,000,000 documents. “it is” in about 265,000,000 documents. “it is possible” in about 72,000,000 documents. “it is possible by” in about 235,000 documents. “it is possible by chance” in about 142,000 documents. “it is possible by chance alone” in 3 documents. Searches for ‘a’ and ‘the’ give about 25,000,000,000 documents. Therefore the chance of any document containing the sentence is 1 in 8,000,000,000. Or a probability of .0000000001. Hence the probability of the phrase occurring twice in a corpus of student submissions?
“To google” 1. Take a phrase from a student’s submission. 4. Examine each hit against the submission & attempt to find similarities. 2. Type the phrase into google. 3. Download the top ten hits.
13 documents from the IEEE digital library 3 random 6 word phrases from each See : Kaner, C. & Fiedler, R.L., ‘A Cautionary Note on Checking Software Engineering Papers for Plagiarism’ IEEE Transaction on Education, 51(2) pp 184-8 2008 “. . . [skimming] each paper, looking for one or more memorable phrases to conduct a manual, full text search . . . “.
13 random documents from the ACM digital library 3 random 6 word phrases from each
13 random Wikipedia articles 3 random 6 word phrases from each
Searches using documents from the International Index of the Performing Arts and from the Academic OneFile database IIPA Academic OneFile (using Google) (using Google) (using Yahoo) (using Yahoo)
Idioms & Statistics Sentences are produced by a mixture of statistical and idiomatic construction. Statistical: That would be a parochial matter. Idiomatic : That would be an ecumenical matter.
Is six words sufficient? Google is the largest corpus of documents on the planet. The proportion of stop words in Google mirrors those in established corpora. Hence Google searches are (at least) as indicative as BNC or ANC searches. Idioms can be automatically excluded as they would yield a large number of hits. (e.g. "that would be an ecumenical matter“ appears 805,000 times.) So can we conclude that the presence of a pre-existing 6 word string is indicative of academic misconduct?
“To automatically google” 1. Take a randomphrase from a student’s submission. 2. Search for the phrase on google. 4. Examine each hit against the submission & attempt to find similarities. 3. If more than n hits are returned, choose another phrase, otherwise download the documents