Work sampling is the statistical technique for determining the proportion of time spent by workers in various defined categories of activity (e.g. setting up a machine, assembling two parts, idle etc). The process of making a number of observations in a random manner at random intervals of time over a particular period (of time) as well group of employees, processes, machines etc. The calculations are done on a percentage basis wherein we record the happenings at every instant & take into consideration of the percentage of activities taking place in that time frame.
Is a sampling method and makes use of the theory of probability. We use a sample which represents the population is used for the purpose of sampling.
Applications of Work Sampling
1. Used for comparing between the idle and working time, this is the foundation for ratio studies.
2. Widely used as a work measurement technique.
3. Used for preparing performance index.
Main Features of Work Sampling: Dependent on work conditions.
(a) Availability of time for carrying out the particular process/ study.
(b) This method can only be used when we need to study the actions performed by a number of people.
(c) Long cycle time: the job which has to be studied should be spread over a longer time span.
(d) The job should be non repetitive so that people don’t get bored of the job.
Steps involved in sampling study
1. Defining the tasks which need to be analyzed.
2. Defining different elements of the task & breaking down that task by defining various categories like idle time, waiting time and absence.
3. Designing the type of study by designing, recording and estimating the shifts, days etc. needed for the study.
4. Identifying the people who will be involved in sampling and other study and starting with the study.
5. After conducting the study analyzing the results.
Example: A worker working in shifts does work for some part of time and remains idle for rest of the time. Let us suppose that there are 60 observations, out of which there were 57 working and 3 idle observations.
Here, idle time % = (3/60) = 5
Working Time % = (57/60) = 95
If a worker works in a shift of 8 hrs (480 min), idle time is 24 min and working time is 456 min.
1. It’s an economical method of doing the time study of work.
2. It is a highly flexible method wherein data can be collected anytime without affecting the results.
3. Chance of day to day or weekly variation are reduced since the time span of taking observation is wide.
4. These methods are less tedious and fatiguing.
1. It’s not an economical process when a single operator/ machine is involved.
2. Doesn’t provide any elemental time data.
3. The process of work study is difficult to understand compared to time study.
4. The working pattern may be changed by the workers and then it becomes difficult and results may be erroneous.