Critical path analysis

Network diagrams such as these allow managers to identify the relationship between different activities within the same project. 

Critical path analysis allows managers to identify which tasks are dependent upon the completion of an earlier activity. It shows the scheduling of activities in a complex project which must be completed in the shortest possible time. It also shows the flexibility in timing non-critical activites.

It allows managers to accurately estimate when the project will be completed.

This shows the earliest time at which the following activity can be started. It is completed from left to right through the network. If more than one arrow feeds into a node,it is the longest preceding activity that determines the EST. 

This shows the time by which an activity must be completed. It shows the latest finishing time of the preceding activities.  Calculating the LFT provides the deadlines which must be met in order for the project to be completed on time.