Time study is a structured process of directly observing and measuring human work using a timing device to establish the time required for completion of the work by a qualified worker when working at a defined level of performance.
Time study is a work measurement technique for recording the times and rates of working for the elements of a specified job carried out under specified conditions and for analyzing the data so as to obtain the time necessary for carrying out the job at a defined level of performance.

In time study, the rating factor is applied to determine Fixation of incentive rate.

Work sampling is the statistical technique for determining the proportion of time spent by workers in various defined categories of activity.
Work sampling is used for determining allowances in time study

Standard time is equal to (Normal time) + (allowances).
The standard time is the time required by an average skilled operator, working at a normal pace, to perform a specified task using a prescribed method.