Enige aspecten van de spreiding van arbeidsprestaties

Some aspects of the spread observed in time studies. In the introduction the importance of time studies in mass production is mentioned. Next figures 1, 2 and 3 give some examples of the frequency distributions observed for the time intervals required for cyclical factory operations. It is pointed out that for comparing different jobs the specific deviation, s/√t, is often more useful than the standard deviation, s, or the average time t̄. If greater detail is required a study of the historic sequency may be of advantage; this sometimes reveals marked periodicity in speed (fig. 5). If one cyclical operation is split up in a number of phases, the variance of the whole is often larger than the sum of the variances of th; components, wich demonstrates the existence of correlations. Sometimes the distribution of 1/t or of 1/t2 is found to be slcser to normal than that oft. In ajinal section the main causes of variation are briefly surveyed.