work measurement

[′wərk ‚mezh·ər·mənt] (industrial engineering) Determination of the difficulty of a given task by using both physiologic and biomechanical parameters to evaluate compatibility of available motions with motions required to perform the task. ergonometrics

Work measurement

The determination of a set of parameters associated with a task. There are four reasons, common to most organizations whether profit seeking or not, why time, effort, and money are spent to measure the amount of time a job takes. These are cost accounting, evaluation of alternatives, acceptable day's work, and scheduling. The fifth, pay by results, is used only by a minority of organizations.

There are three common ways to determine time per job: stopwatch time study (sequential observations), occurrence sampling (nonsequential observations), and standard data.

Three levels of detail for standard time systems
Micro system (typical component time range from 0.01 to 1 s; MTM
nomenclature)
Element	Code	Time

Reach	R10C	12.9 TMU*
Grasp	G4B	9.1
Move	M10B	12.2
Position	P1SE	5.6
Release	RL1	2.0

Elemental system (typical component time range from 1 to 1000 s)

Element		Time

Get equipment		1.5 min
Polish shoes		3.5
Put equipment away		2.0

Macro system (typical component times vary upward from 1000 s)

Element		Time

Load truck		2.5 h
Drive truck 200 km		4.0
Unload truck		3.4
27.8 TMU = 1 s; 1 s = 0.036 TMU. source: S. A. Konz, Work Design*, published by Grid, 4666 Indianola Avenue, Columbus, OH 43214, 1979.

Stopwatch time study can be used for almost any existing job. It is reasonable in cost and gives reasonable accuracy. However, it does require the worker to be rated. Once the initial cost of standard data system has been incurred, standard data may be the lowest-cost, most accurate, and most accepted technique.

Occurrence sampling is also called work sampling or ratio-delay sampling. If time study is a “movie,” then occurrence sampling is a “series of snapshots.” The primary advantage of this approach may be that occurrence sampling standards are obtained from data gathered over a relatively long time period, so the sample is likely to be representative of the universe. That is, the time from the study is likely to be representative of the long-run performance of the worker.

Reuse of previous times (standard data) is an alternative to measuring new times for an operation. There are three levels of detail: micro, elemental, and macro (see table). Micro-level systems have times of the smallest component ranging from about 0.01 to 1 s. Components usually come from a predetermined time system such as methods-time-measurement (MTM) or Work-Factor. Elemental level systems have the time of the smallest component, ranging from about 1 to 1000 s. Components come from time study or micro-level combinations. Macro-level systems have times ranging upward from about 1000 s. Components come from elemental-level combinations, from time studies, and from occurrence sampling. See Methods engineering, Performance rating, Productivity

work measurement

an aspect of WORK STUDY which involves the application of measurement techniques to establish the time it takes for a trained worker to carry out a particular JOB. The purpose of measuring the time required to complete a job is to provide management with information for PRODUCTION SCHEDULES, for PRODUCT COSTING, and to assist in the design of incentive payment systems such as PIECEWORK.

Timestudy is the most often used work measurement technique for recording the time it should take to complete a specified job. Time study involves a number of steps:

Recording details of the job and checking that no obvious improvements in method can be made (see METHOD STUDY);
Dividing up the job being done into discrete operational elements to facilitate the timing of each component element;
Timing the work elements to obtain the observed time;
Rating the performance of the worker by comparing his or her actual rate of working against the defined STANDARD RATE (the average rate of working of a skilled, motivated operative) and using this to adjust the observed time and arrive at the basic time;
Determining the percentage allowances to be added to the basic time to compensate for fatigue, contingencies like machine breakdowns and interruptions, in order to establish the standard time for the job.

Time study is appropriate for short-cycle repetitive work. If, however, it is necessary to establish work standards in situations where irregular long-cycle work is conducted or where many different jobs are performed, these techniques may well be quite inappropriate. In such circumstances it may well be advisable to use some form of activity sampling, which in its simplest form consists of visual sampling and recording of activities in order to establish the proportion of time in which employees or machines are working or idle (see ACTIVITY CHART).

Time study is a direct work measurement technique. Alternatively, various indirect measures may be employed to generate standard times. One method uses data collected from previous time studies to provide a synthetic standard time for a job which differs only marginally from a job which has already been subject to direct time study or a new job which has not yet begun. A second method, the predetermined motion time system lists all motions that workers can utilize in performing tasks, together with times for these motions. From this general list of motions it is possible to select the specific motions involved in a particular job and thus compile a standard time for this particular job. Finally, analytical estimating can be used where there is insufficient synthetic data available to allow time standards to be established for all job elements and where the time required for these elements has to be based on knowledge and practical experience. See SIMULTANEOUS MOTION CHART, THERBLIGS.