Effects of scheduled overtime on labor productivity

This paper reviews the construction literature on the effects on labor productivity of scheduled overtime. The literature is organized into three groups: studies based on data from project records, studies in which the sources of data are unknown, and studies done in the manufacturing sector. Analyses are also performed on the influence of the number of days per week and the number of hours per day. The literature on scheduled overtime was found to be very sparse; dated to the late 1960s and earlier; based on small sample sizes; and largely developed from questionable or unknown sources. The analysis reveals very few original data. Many studies reference other studies, giving the false appearance of originality. The analysis of data shows general consistency with respect to overall losses of efficiency. However, with respect to the loss of efficiency as a function of the number of hours per day and the number of days per week, many studies show that the effect of these two variables is negligible. The paper concludes that these studies provide strange and largely unbelievable results.