Connors, Robert J., and Andrea A. Lunsford. "Frequency of Formal Errors in Current College Writing, or Ma and Pa Kettle Do Research." CCC 39.4 (1988): 395-409.

Abstract:

The authors, who had studied the history of marking and classifying student writing errors, conducted a study of 3,000 teacher-marked papers of American college freshmen and sophomores to analyze and determine the most common patterns of student writing errors made in the 1980s and which formal and mechanical errors were marked most consistently by American teachers. After generating their own taxonomy of the twenty most common student errors, the authors used fifty raters to analyze the student papers. Their results included finding that college English teachers do not always agree on what is a serious writing error, that teachers mark only 43% of the most serious errors in the papers they grade, and that teachers are less likely to mark an error that requires extensive explanation. This study also debunks claims of educational decline, since the authors, comparing their findings to the results of past studies of student writing errors, found that students in the 1980s make approximately the same number of errors as students earlier in the century.