13.7 Suppose it were known that one of two authors wrote a particular article, but a decision as to which was the correct author was difficult. Suppose further that N1 previous articles of author number (1) were available, and N2 previous articles of author number (2) were available. Assume that all authors can be distinguished from one another on the basis of the frequencies with which they use certain words in their writings. Describe the procedure you would use to determine which of the two authors in question wrote the article. (See also Mosteller and Wallace, 1964.)