A Study of Errors, Error-Proneness, and Error Diagnosis in Cobol
This paper provides data on Cobol error frequency
for correction of errors in student-oriented 
compilers, improvement of teaching, and changes in programming
language.  Cobol was studied because of 
economic importance, widespread usage, possible error-including
design, and lack of research.  The types 
of errors were identified in a pilot study; then, using
the 132 error types found, 1,777 errors were 
classified in 1,4000 runs of 73 Cobol students.  Error
density was high: 20 percent of the types contained 
80 percent of the total frequency, which implies high
potential effectiveness for software based correction 
of Cobol.  Surprisingly, only four high-frequency errors
were error-prone, which implies minimal error 
inducing design. 80 percent of Cobol misspellings were classifiable
in the four error categories of previous 
researchers, which implies that Cobol misspellings
are correctable by existent algorithms.  Reserved 
word usage was not error-prone, which implies minimal
interference with usage of reserved words.  Over 
80 percent of error diagnosis was found to be inaccurate.
 Such feedback is not optimal for users, particularly 
for the learning user of Cobol.
CACM January, 1976
Litecky, C. R.
Davis, G. B.
