Improving Productivity Estimates by Work Sampling
Publication: Journal of Construction Engineering and Management
Volume 110, Issue 2
Abstract
Theoretical aspects are presented to evaluate the adequacy of work sampling as a surrogate productivity measure. A 10‐week study is described in which work sampling data were gathered simultaneously with earned value information for a 10‐man, small‐bore pipefitter crew. Two forms of work sampling data were gathered that differed principally in the definition of direct work. The direct work percentages are statistically correlated to the ratio of earned to actual man‐hours, and it is shown that the Pearson product‐moment correlation coefficient could be improved by as much as 86% if the definition of direct work is restricted. The probability of a Type I statistical error is also greatly reduced. Data summarized according to 5‐ or 7‐day moving averages is found to be more reliable than daily or weekly averages. It is shown how a prediction equation could be developed. The slope of this equation suggests that rather significant changes in the earned to actual man‐hour ratio are reflected by rather small changes in direct work.
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References
1.
Mendenhall, W., Introduction to Probability and Statistics, Duxbury Press, North Scituate, Mass., 1979.
2.
Richardson, W. J., Cost Improvement, Work Sampling and Short Interval Scheduling, Reston Publishing Company, Inc., Reston, Va., 1976.
3.
SAS User's Guide, SAS Inst., Inc., Raleigh, N.C., 1978.
4.
Thomas, H. R., and Holland, M. P., “Work Sampling: A Comparative Analysis,” Journal of the Construction Engineering and Management Division, ASCE, Vol. 106, No. CO4, Paper 15879, Dec., 1980, pp. 519–534.
5.
Thomas, H. R., Holland, M. P., and Gustenhoven, C. T., “Games People Play with Work Sampling,” Journal of the Construction Engineering and Management Division, ASCE, Vol. 108, No. CO1, Paper 16906, Mar., 1982, pp. 13–22.
6.
Thomas, H. R., “Construction Work Sampling,” Construction Management Research Report No. 14, The Business Roundtable, Pennsylvania State Univ., Dept. of Civ. Engrg., University Park, Pa., 1981.
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Thomas, H. R., and Daily, J., “Crew Performance Measurement Via Activity Sampling,” Journal of the Construction Engineering and Management Division, ASCE, Vol. 109, No. CO3, Paper 18218, Sept., 1983.
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Copyright © 1984 ASCE.
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Published online: Mar 1, 1984
Published in print: Mar 1984
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