The time taken by a trained worker to perform an operation, while working a steady pace, is known as Standard time.

String diagram is one of the useful and simplest techniques of method study.
It can be defined as a scale model on which a thread is used to trace the path or movements of man and materials during a specified sequence of events.
It can also be stated that string diagram in a special form of flow diagram.

A diagram showing the path followed by men and materials while performing a task is known as Flow diagram.

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.