What is Work Sampling?


Work sampling is a method of finding the percentage occurrence of a certain activity by statistical sampling and random observations.

In order to obtain a complete and accurate picture of the productive time and idle time of the machines in a specific production area, it would be necessary to observe continuously all the machines in that area and to record when and why any of the machines were stopped. It would of course be quite impossible to do this unless a large of workers spent the whole of their time on this task alone – an unrealistic proposition.

If it were possible to note at a glance of every machine, it may be found that, 80% of machines are working and 20% were stopped. If this action was repeated 20 or more times at different times of the day and if each time the proportion of machines working was always 80%, it would be possible to say with confidence that at any given time there were always 80% of the machines working.

As it is not generally possible to do this either, the next best method has to be adopted; that of making tours of the factory at random intervals, noting which machines are working and which are stopped, an noting the cause of each stoppage. This data capturing method is known as work sampling.

The larger the size of the sample, the more accurate or representative it becomes with respect to the original “population”, or group of items under consideration.

Case Study: Work Sampling for Sewing Floor
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