Work sampling is a method in which the job is sampled at random intervals to determine the proportion of total time spent on a particular task.[46] It provides insight into how often workers are performing tasks which might cause strain on their bodies. In a work sampling study, a large number of observations are made of the workers over an extended period of time. For statistical accuracy, the observations must be taken at random times during the period of study, and the period must be representative of the types of activities performed by the subjects. One important usage of the work sampling technique is the determination of the standard time for a manual manufacturing task. Similar techniques for calculating the standard time are time study, standard data, and predetermined motion time systems