Performance Rating:
Performance rating is that process,
during which the time study engineer compares the performance of the operator
under observation with his own concept of normal performance.
Performance Rating is the step in the
work measurement in which the analyst observes the worker’s performance and
records a value representing that performance relative to the analyst’s concept
of standard performance.
In mathematical term,
The concept of normal performance, must be such that the time standards are set from it, are within the capacity of the majority of workers in the enterprise.
It would be of no use in setting
standards so high that only the best worker could attain them since programmes
or estimates based on them would never be fulfilled.
Allowances:
To get the standard time, a proper
allowance must be added considering the working conditions.
While deciding the quantum (generally in terms
of percentages) of allowance to be added to the normal time, following types of allowances are considered:
1.
Relaxation Allowance:
This allowance depends upon the nature of the
job, and includes following two categories of allowances:
(A) Personal Need Allowance:
It provides for the necessity to go away
from the work place to attend the personal needs such as washing, going to
lavatory, getting a drink etc. It is commonly taken as 5% for male and 7% for
female worker.
(B) Fatigue Allowance:
Fatigue allowance is provided to recover
a worker from the physiological and psychological effect of carrying out work.
2.
Interference Allowance:
When one worker is attending more than
one machine, then, interference is the time for which one or more machine units
remain idle while attendant is occupied with the work on other machine units.
The allowance provided to compensate this idleness due to interference is known
as interference allowance.
3.
Process Allowance:
This is an allowance provided to
compensate for enforced idleness during a process. This includes loss of time
due to (t) no work (ii) power failure, (iii) faulty material, (iv) faulty tools
or equipment’s.
4.
Contingency Allowance:
This is an allowance of time to meet
legitimate, irregular and infrequent items of work or delays which cannot
economically be measured correctly. It is usually taken as less than 5%.
5.
Special Allowance:
These allowances are decided as a policy
matter of management. These are allowed for activities which are normally not a
part of the operation cycles but are essential for satisfactory performance of
work.
Work Sampling:
Work sampling is a statistically based
technique utilized for analysing work performance and machine utilization by
direct observation, but without a stop watch. So work sampling is another
useful technique of work study.
This technique is particularly useful to
estimate the proportion of delays or idleness’s occurring in a enterprise/plant
and attributing the cause for it, such as power failures/input delays, machine
cleaning, machine breakdowns and manpower idling or in other words, estimating
proportion of time spent by an executive in attending meetings, telephoning or
reading etc.
The stop watch technique for time
estimation is extremely time consuming and therefore not feasible.
Work sampling is a technique for
establishing standard times of activities. This method also known as activity
sampling was devised by L.H.C. Tippet in 1934. This technique is more suitable
for analysing group activities and repetitive activities which take longer
duration.
If a given individual performs more than
one activity, then the time standard for each activity can be computed with the
help of this method. For example, on a printing press, a single operator/worker
will be doing composing, proofreading, printing etc. The time standards for all
these activities can be determined with the help of work sampling method.
The method of work sampling consists of
taking a large number of instantaneous observations randomly, rather than
taking observations continuously as is done in various production
investigations/ studies. This method is a sampling technique and depends upon
laws of probability.
A sample taken at random from a large
population provides a good estimate of the distribution of the population
because it tends to have the same distribution as the population.
Some examples are as follows:
(1) A decision regarding the cooking of
rice is taken by having a sample of rice from a boiling/ cooking pot and
pressed between fingers.
(2) A decision regarding the quality of
wheat bag to be purchased is made by examining a sample of wheat from a bag.
Hence, work sampling is a technique of
determining the percentage occurrences of a certain activity (a group of
processes, machines, or workers) with the help of statistical sampling and
random observations. When the sample size is large enough and random
observations are made indeed, there is quite a high probability that the
observations would reflect the real situation plus minus a certain margin of
error.
Definition
of Work Sampling:
“Work sampling is a method in which a
large number of instantaneous observations are made at random time intervals
over a period of time or a group of machines, workers or processes/operations.
Each observation records what is happening at that instant and the percentage
of observations recorded for a particular activity or delay/idleness is a
measure of the percentage of time during which that activity or delay/idleness
occurs”.
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