2. the length of time required for a worker to do a certain thing.
3. the amount of rest and the time of rest required to overcome fatigue.
Dr. Taylor spent years in determining the percentage of rest that should be allowed in several of the trades, beginning with those where the making of output demands weight hanging on the arms; but there is still a great amount of investigation that could be done to advantage to determine the most advisable percentage of rest in the working day of different lengths of hours. Such investigation would probably show that many of our trades could do the same amount of work in fewer hours, if the quantity and time of rest periods were scientifically determined.
Again, there is a question of the length of each rest period. It has been proven that in many classes
of work, and especially in those where the work is interrupted periodically by reason of its peculiar nature, or by reason of inefficient performance in one of the same sequence of dependent operations, alternate working and resting periods are best. There is to be considered in this connection, however, the recognized disadvantage of reconcentrating the attention after these rest periods. Another thing to be considered is that the rate of output does not decline from the beginning of the day, but rather the high point of the curve representing rate of production is at a time somewhat later than at the starting point. The period before the point of maximum efficiency is known as "warming up" among ball players, and is well recognized in all athletic sports.
As for the point of minimum efficiency, or of greatest fatigue, this varies for "morning workers," and "night workers." This exemplifies yet another variable.
The minuteness of the sub-fields that demand observation, is shown by an entry in the Psychological Index: "1202. Benedict, F.G. "Studies in Body — Temperature." 1. Influence of the Inversion of the Daily Routine; the Temperature of Night Workers."[14]
Selection of Best Unit of Measurement Necessary and Important. — Selecting the unit of measurement that will of itself reduce costs is a most important element in obtaining maximum efficiency.[15] This is seldom
realized. [16] Where possible, several units of measurements should be used to check each other. [17] One alone may be misleading, or put an incentive on the workers to give an undesirable result.
The rule is, — always select that unit of output that will, of itself, cause a reduction in costs.