Time is a key factor on which the success of any project depends. Timing limits are the most critical, and completing a project on time is a difficult task. At the initial stage, it is important to correctly determine the subject area and scope of the project. In order not to make adjustments to the calendar schedule in the future and to avoid problems in the implementation process.
In order to cope with time constraints, various methods are used in project management, one of which is the PERT assessment method. Before you figure out what it is, what are its features, advantages and disadvantages, the article discusses the concepts of a calendar schedule and project timing management, as well as the term "critical path".
Schedule and Five Time Management Processes
For the timely completion of the project and achieving an effective result, the timing of the project must be professionally managed. If time is delayed, the negative consequences are budget overruns and insufficient quality of work. The main project time management tool is a schedule that is sequentially developed using five interrelated processes:
- The scope of work and production methods are determined.
- The sequence of actions and their relationship is established.
- The duration of each work and the total duration are estimated.
- A schedule is being developed.
- The management of changes in the schedule.
The project contains key events, without which further continuation is not possible. Such events are called milestones. In the course of the project, the project is subject to deviations, and the task of managing the deadlines is to reduce their number and reduce the amount. To do this, you need to control:
- milestone achievement dates;
- cost indicators of achievement;
- compliance of the achieved results with the planned.
In standard projects, the experience of previously implemented programs is used to determine the timing and sequence of work. But due to the fact that each new one is unique, the accumulated knowledge is partially applied.
Types of Calendar Plans
Schedules are divided into three types: basic, executable, actual. The basic plan is an officially approved schedule, with which subsequently the executable and actual data received during the implementation of the project are compared. The executable plan contains a complete list of works with characteristics and relationships and is a Gantt network diagram. The actual plan is a schedule that changes and is supplemented with the implementation of the project and the receipt of information on the actual performance of work.
If the actual performance begins to differ from the baseline, an operational decision is made to take corrective actions.
The critical path of the project
In the project, work is performed sequentially or in parallel. In sequential production, the start and end dates of some depend on the schedule of others. There are four types of job dependency:
- "finish start" - the completion of one work depends on the start of another;
- “start-finish” - the beginning of one action depends on the end of another;
- "start-start" - the start of one job depends on the start of another;
- "finish-finish" - the end of one activity depends on the end of another.
In parallel execution, these actions are independent of each other and are performed at any time.
The critical path determines the longest sequence of work, which in the end will not affect the completion date of the entire project. He indicates the critical work, the final term depends on the beginning and end of which. In case of deviation from the schedule, the critical path works are analyzed with subsequent adjustment. The following methods are used for this:
- re-evaluation of the duration of work;
- additional detailing of work;
- search for alternative ways to implement the project;
- parallel execution of work;
- increase in the amount of resources;
- organization of overtime work.
PERT - project assessment and analysis
In large, complex and long-term research projects, it is difficult to determine the timing of work and develop a detailed schedule. The PERT method is intended for them, which stands for the method of project assessment and analysis and is used when the exact duration of the work is unknown.
What are the differences between the methods
There are differences between the two methods of project analysis:
- The critical path is focused on the duration of the work, and the PERT method is focused on key events (milestones).
- The critical path is used when there is an accurate estimate of the project’s work time, and PERT is used for programs where it is problematic to predict the duration.
- The critical path method has any type of dependency, and the PERT method is used for one thing - a “finish start".
Calculation formula
According to the PERT method, project management is the control over the total duration with the existing uncertainty of work. To apply it and calculate the duration of work, three estimates are used:
- A likely estimate is the period of time when there is a high probability of completion.
- Optimistic - the shortest time for which the production process is carried out.
- A pessimistic assessment is the longest time it takes to complete a job.
The calculation formula for the PERT analysis is as follows: duration = (shortest time + 4 x probable time + longest time) / 6
Advantages and disadvantages
The table below discusses the advantages and disadvantages of using the PERT method:
Benefits | disadvantages |
This method is useful when the project is new and there is little information on the timing of the implementation of such action plans. | The human factor, subjective analysis and inaccurate estimates can affect the schedule. |
The method simplifies planning and reduces project uncertainty. | Updating and maintaining the schedule requires a lot of time and money. |
The method gives the exact date of completion of the project. | Difficulty in management, there is no guarantee that the schedule will remain unchanged throughout the project. |
The priority task of time management is to understand whether it is necessary to intervene in the course of the project to return time constraints to the basic framework. For a quick analysis of the program’s timelines, it is important to develop a detailed, convenient and detailed calendar chart. In the case of large-scale projects, when it is difficult to determine the exact terms of the work, using the PERT method, you can develop the optimal schedule and calculate the most likely dates for the implementation of the action plan.