"Ridley and Sammour (1996) examined student performance and satisfaction in courses delivered online...."

“Ridley and Sammour (1996) examined student performance and satisfaction in courses delivered online. The problem addressed in their study was to determine how best to re-design degree programs and course offerings to improve institutional effectiveness, while at the same time providing a high-quality program with convenient student access. The authors used an Instruction Evaluation Survey (IES) to cull information from online students and from instructors who taught both online and traditional courses. Because students typically self-select into such classes, convenience sampling was used in the distribution of the survey. Performance data for online and traditional courses was obtained from the instructors. They noted a high rate of withdrawal from online classes over two semesters—30.0% and 25.0%, respectively.”

- The Technology Source Archives - Online Drop Rates Revisited