Time Study

TIME STUDY (German: Zeitermittelung, French: chronométrie, English: time study), the determination of the duration of work processes and their constituent elements. Its primary and main application is for determining production norms. The main varieties of time study are: 'workday photography' (a term used only in the USSR) and chronometry proper. 'Workday photography' consists of continuous, protocol-based observation of a worker throughout the entire day; the alternation of various types of work (e.g., primary, auxiliary, incidental, etc.) and downtime (due to accidents, lack of material, for rest, etc.) is noted; as a result, the amount of time spent during the day on various types of work and downtime is established; observation is conducted with the help of a clock, with an accuracy of up to 1 minute, sometimes even up to 5 minutes. Chronometry proper consists of measuring the duration of individual operations performed by a worker (e.g., manufacturing one piece of a product); in view of the high accuracy (usually up to 1 second, and recently 0.01 minutes is widely used), measurements are made with the help of a stopwatch. The latter has the appearance and, in principle, the mechanism of a pocket watch, but with a large, full-dial second hand and a small minute hand (the hour hand is absent) (Fig. 1). In some stopwatches, the dial is divided into 100 parts, which greatly facilitates calculations. A feature of the mechanism is that it is set in motion by pressing the crown; a second press stops the hands, and a third returns them to the zero position. Stopwatches with a double second hand are convenient; their additional hand, usually moving together with the main one, can be stopped by pressing a special button; by a second press on the same button, the additional hand is reconnected to the main one that has moved ahead and continues to move with it; this allows for measuring a series of sequential operations without stopping the stopwatch, but merely pausing the additional hand for an accurate reading of its position. In some cases, the Taylor summing stopwatch is convenient, in which the hands do not return to zero but are only stopped and restarted from the same point. For very precise measurements, there are stopwatches that make a revolution of the main hand not in 1 minute, but in 10 seconds, 6 seconds, and even 3 seconds. Standard single- and double-hand stopwatches are manufactured in the USSR (Tochmekh factory, price 75-90 rubles). To determine the typical duration of an operation, repeatedly performed measurements are subjected to variational-statistical processing. The usual type of distribution curve for time measurements with a sufficiently large number of them is: asymmetric, with the mode shifted to the left of the arithmetic mean (i.e., toward a shorter time) and, for the most part, with a secondary mode in the right part (Fig. 2). In view of the presence of characteristic differences in 'workday photography' and in the distribution curve of time measurements at different hours of work, time study was proposed by Bruzhes, along with other individuals, as a method of the physiology of labor and found wide application in this field. The main shifts are: in 'workday photography' under the influence of fatigue: 1) increased frequency of rest breaks (their lengthening in this case is an indicator of a deeper degree of fatigue), 2) lengthening of downtime for technical reasons (hidden rest), 3) shortening of periods of primary work (violation of work rhythm), 4) increased frequency of changes in different types of work (the same), 5) replacement of standing rests with sitting rests during standing work (and vice versa for sitting work). Shifts in the distribution curve of time measurements (Fig. 3): 1) shift of the arithmetic mean to the right with an unchanged mode (a shift of the mode to the right testifies to very deep fatigue—a violation of automatism), 2) increase in the secondary mode (due to the introduction of micro-rests into the operation), 3) decrease in kurtosis (the same).