Work measurement is the application of techniques designed to establish
the time for a qualified worker to carry out a specified job at a defined level of
The Purpose of Work Measurement
Method study is the principal technique for reducing the work involved,
primarily by eliminating unnecessary movement on the part of material or operatives and by
substituting good methods for poor ones. Work measurement is concerned with investigating,
reducing and subsequently eliminating ineffective time, that is time during which no
effective work is being performed, whatever the cause.
Work measurement, as the name suggests, provides management with a
means of measuring the time taken in the performance of an operation or series of
operations in such a way that ineffective time is shown up and can be separated from
effective time. In this way its existence, nature and extent become known where previously
they were concealed within the total.
The Uses of Work Measurement
Revealing existing causes of ineffective time through study, important
though it is, is perhaps less important in the long term than the setting of sound time
standards, since these will continue to apply as long as the work to which they refer
continues to be done. They will also show up any ineffective time or additional work which
may occur once they have been established.
In the process of setting standards it may be necessary to use work
- To compare the efficiency of alternative methods. Other conditions being equal, the
method which takes the least time will be the best method.
- To balance the work of members of teams, in association with multiple activity charts,
so that, as nearly as possible, each member has a task taking an equal time to perform.
- To determine, in association with man and machine multiple activity charts, the number
of machines an operative can run.
The time standards, once set, may then be used:
- To provide information on which the planning and scheduling of production can be based,
including the plant and labour requirements for carrying out the programme of work and the
utilisation of available capacity.
- To provide information on which estimates for tenders, selling prices and delivery
promises can be based.
- To set standards of machine utilisation and labour performance which can be used for any
of the above purposes and as a basis for incentive schemes.
- To provide information for labour-cost control and to enable standard costs to be fixed
It is thus clear that work measurement provides the basic information
necessary for all the activities of organising and controlling the work of an enterprise
in which the time element plays a part. Its uses in connection with these activities will
be more clearly seen when we have shown how the standard time is obtained.
Techniques of work measurement
The following are the principal techniques by which work measurement is
1. Time study
2. Activity sampling
3. Predetermined motion time systems
4. Synthesis from standard data
6. Analytical estimating
7. Comparative estimating
Of these techniques we shall concern ourselves primarily with time
study, since it is the basic technique of work measurement. Some of the other techniques
either derive from it or are variants of it.
1. Time Study
Time Study consists of recording times and rates of work for elements
of a specified job carried out under specified conditions to obtain the time necessary to
carry out a job at a defined level of performance.
In this technique the job to be studied is timed with a stopwatch,
rated, and the Basic Time calculated.
1.1 Requirements for Effective Time Study
The requirements for effective time study are:
a. Co-operation and goodwill
b. Defined job
c. Defined method
d. Correct normal equipment
e. Quality standard and checks
f. Experienced qualified motivated worker
g. Method of timing
h. Method of assessing relative performance
i. Elemental breakdown
j. Definition of break points
k. Recording media
One of the most critical requirements for time study is that of
elemental breakdown. There are some general rules concerning the way in which a job should
be broken down into elements. They include the following. Elements should be easily
identifiable, with definite beginnings and endings so that, once established, they can be
repeatedly recognised. These points are known as the break points and should be clearly
described on the study sheet. Elements should be as short as can be conveniently timed by
the observer. As far as possible, elements - particularly manual ones - should be chosen
so that they represent naturally unified and distinct segments of the operation.
1.2 Performance Rating
Time Study is based on a record of observed times for doing a job
together with an assessment by the observer of the speed and effectiveness of the worker
in relation to the observer's concept of Standard Rating.
This assessment is known as rating, the definition being given in BS
The numerical value or symbol used to denote a rate of working.
Standard rating is also defined (in this British Standard BS3138) as:
"The rating corresponding to the average rate at which qualified
workers will naturally work, provided that they adhere to the specified method and that
they are motivated to apply themselves to their work. If the standard rating is
consistently maintained and the appropriate relaxation is taken, a qualified worker will
achieve standard performance over the working day or shift."
Industrial engineers use a variety of rating scales, and one which has
achieved wide use is the British Standards Rating Scale which is a scale where 0
corresponds to no activity and 100 corresponds to standard rating. Rating should be
expressed as 'X' BS.
Below is an illustration of the Standard Scale:
Rating Walking Pace
0 no activity
50 very slow
100 brisk (standard rating)
125 very fast
150 exceptionally fast
The basic time for a task, or element, is the time for carrying out an
element of work or an operation at standard rating.
Basic Time = Observed Time x Observed Rating
The result is expressed in basic minutes - BM's.
The work content of a job or operation is defined as: basic time +
relaxation allowance + any allowance for additional work - e.g. that part of contingency
allowance which represents work.
1.3 Standard Time
Standard time is the total time in which a job should be completed at
standard performance i.e. work content, contingency allowance for delay, unoccupied time
and interference allowance, where applicable.
Allowance for unoccupied time and for interference may be important for
the measurement of machine-controlled operations, but they do not always appear in every
computation of standard time. Relaxation allowance, on the other hand, has to be taken
into account in every computation, whether the job is a simple manual one or a very
complex operation requiring the simultaneous control of several machines. A contingency
allowance will probably figure quite frequently in the compilation of standard times; it
is therefore convenient to consider the contingency allowance and relaxation allowance, so
that the sequence of calculation which started with the completion of observations at the
workplace may be taken right through to the compilation of standard time.
A contingency allowance is a small allowance of time which may be
included in a standard time to meet legitimate and expected items of work or delays, the
precise measurement of which is uneconomical because of their infrequent or irregular
A relaxation allowance is an addition to the basic time to provide the
worker with the opportunity to recover from physiological and psychological effects of
carrying out specified work under specified conditions and to allow attention to personal
needs. The amount of the allowance will depend on the nature of the job. Examples are:
Energy output 0-10%
e.g. Electronics 5%
Other allowances include process allowance which is to cover when an
operator is prevented from continuing with their work, although ready and waiting, by the
process or machine requiring further time to complete its part of the job. A final
allowance is that of Interference which is included whenever an operator has charge of
more than one machine and the machines are subject to random stoppage. In normal
circumstances the operator can only attend to one machine, and the others must wait for
attention. This machine is then subject to interference which increased the machine cycle
It is now possible to obtain a complete picture of the standard time
for a straightforward manual operation.
2. Activity Sampling
Activity sampling is a technique in which a large number of
instantaneous observations are made over a period of time of a group of machines,
processes or workers. Each observation records what is happening at that instant and the
percentage of observations recorded for a particular activity or delay is a measure of the
percentage of time during which the activity or delay occurs.
The advantages of this method are that
- It is capable of measuring many activities that are impractical or too costly to be
measured by time study.
- One observer can collect data concerning the simultaneous activities of a group.
- Activity sampling can be interrupted at any time without effect.
The disadvantages are that
- It is quicker and cheaper to use time study on jobs of short duration.
- It does not provide elemental detail.
The type of information provided by an activity sampling study is:
a. The proportion of the working day
during which workers or machines are producing.
b. The proportion of the working day used up by delays. The
reason for each delay must be recorded.
c. The relative activity of different workers and machines.
To determine the number of observations in a full study the following
equation is used:
3. Predetermined Motion Time Systems
A predetermined motion time system is a work measurement technique
whereby times established for basic human motions (classified according to the nature of
the motion and the conditions under which it is made) are used to build up the time for a
job at a defined level of performance.
The systems are based on the assumption that all manual tasks can be
analysed into basic motions of the body or body members. They were compiled as a result of
a very large number of studies of each movement, generally by a frame-by-frame analysis of
films of a wide range of subjects, men and women, performing a wide variety of tasks.
The first generation of PMT systems, MTM1, were very finely detailed,
involving much analysis and producing extremely accurate results. This attention to detail
was both a strength and a weakness, and for many potential applications the quantity of
detailed analysis was not necessary, and prohibitively time -consuming. In these cases
"second generation" techniques, such as Simplified PMTS, Master Standard Data,
Primary Standard Data and MTM2, could be used with advantage, and no great loss of
accuracy. For even speedier application, where some detail could be sacrificed then a
"third generation" technique such as Basic Work Data or MTM3 could be used.
Synthesis is a work measurement technique for building up the time for
a job at a defined level of performance by totaling element times obtained previously from
time studies on other jobs containing the elements concerned, or from synthetic data.
Synthetic data is the name given to tables and formulae derived from
the analysis of accumulated work measurement data, arranged in a form suitable for
building up standard times, machine process times, etc by synthesis.
Synthetic times are increasingly being used as a substitute for
individual time studies in the case of jobs made up of elements which have recurred a
sufficient number of times in jobs previously studied to make it possible to compile
accurate representative times for them.
The technique of estimating is the least refined of all those available
to the work measurement practitioner. It consists of an estimate of total job duration (or
in common practice, the job price or cost). This estimate is made by a craftsman or person
familiar with the craft. It normally embraces the total components of the job, including
work content, preparation and disposal time, any contingencies etc, all estimated in one
6. Analytical estimating
This technique introduces work measurement concepts into estimating. In
analytical estimating the estimator is trained in elemental breakdown, and in the concept
of standard performance. The estimate is prepared by first breaking the work content of
the job into elements, and then utilising the experience of the estimator (normally a
craftsman) the time for each element of work is estimated - at standard performance. These
estimated basic minutes are totalled to give a total job time, in basic minutes. An
allowance for relaxation and any necessary contingency is then made, as in conventional
time study, to give the standard time.
7. Comparative estimating
This technique has been developed to permit speedy and reliable
assessment of the duration of variable and infrequent jobs, by estimating them within
chosen time bands. Limits are set within which the job under consideration will fall,
rather than in terms of precise capital standard or capital allowed minute values. It is
applied by comparing the job to be estimated with jobs of similar work content, and using
these similar jobs as "bench marks" to locate the new job in its relevant time
band - known as Work Group.