Dummy activities are used to Maintain the required net work.

Guidelines for constructing Network Diagrams:
-Each activity is represented by only one arrow.
-An arrow can represent only one activity
-If two or more activities are identified with the same start & end events. Dummy activity / activities need to be introduced in the network
-Before an activity can be started all preceding activities must be completed
-The flow of diagram is from left to right.
-The arrows are not to the scale
-Arrows should be straight
-Unless absolutely unavoidable, arrows should not be crossed.

Bar charts are suitable for Minor works.

Work sampling is the statistical technique used 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.).

It is as important as all other statistical techniques because it permits quick analysis, recognition, and enhancement of job responsibilities, tasks, performance competencies, and organizational workflows. Other names used for it are 'activity sampling', 'occurrence sampling', and 'ratio delay study'.

Work sampling is applied for
- Estimation of the percentage utilization of machine tools.
- Estimating the percentage of the time consumed by various job activities.
- Finding out time standards, specially where the job is not repetitive and where time study by stop watch method.