Suchergebnisse

SummarySome 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.