Exploratory Experimental Studies Comparing Online and Off line Programming Performance Two exploratory experiments were conducted at System Development Corporation to compare debugging performance of programmers working under conditions of on-line and off line access to a computer. These are the first known studies that measure programmers' performance under controlled conditions for standard tasks. Statistically significant results of both experiments indicated faster debugging under online conditions, but perhaps the most important practical finding involves the striking individual differences in programmer performance. Methodological problems encountered in designing and conducting these experiments are described; limitations of the findings are pointed out; hypotheses are presented to account for results; and suggestions are made for further research. CACM January, 1968 Sackman, H. Erikson, W. J. Grant, E. E. online vs. off line performance, programmer/computer communication, programming experimental-empirical studies, programming cost effectiveness, programming performance, debugging effectiveness, time sharing vs. batch processing, factor analysis application, programmer trainee performance, basic programming knowledge test, experienced programmer study, analysis of variance, programmer individual differences 2.40 CA680101 JB February 23, 1978 2:58 PM 267 4 1792 1139 4 1792 1141 4 1792 1215 4 1792 1223 4 1792 1647 4 1792 1781 4 1792 1787 4 1792 1792 4 1792 1792 4 1792 1908 4 1792 364 4 1792 405 4 1792 438 4 1792 763 4 1792 224 5 1792 1605 5 1792 1792 5 1792 1792 5 1792 1792 5 1792 3091 5 1792 1792 6 1792