Was ist die Critical-Path-Methode (CPM)?
CPM is a step-by-step project management technique for identifying activities on the critical path. The approach breaks down a project into work items, displays them in a flowchart, and then calculates the duration of the project based on the estimated timelines for each. Identify time-sensitive tasks.
Der Text A Guide to Project Management Fundamentals (PMBOK®Guide), an internationally recognized collection of processes and knowledge areas considered best practices for the project management profession, defines the critical path as "the sequence of planned activities that determine the duration of the project." It is the longest sequence of tasks in a project plan that must be completed on time for the project to meet its deadline. If there is a delay in a task on the critical path, the entire project will be delayed. While many projects have only one critical path, some projects can have multiple critical paths.
Dr. Larry Bennett, civil engineer, project manager and author of four books including a 1978 guide to the critical path entitled “Critical Path Precedence Networks' explains that the critical path method helps manage projects in two different ways: 'It creates a planned schedule that guides the project team and provides the basis for tracking the performance of the project schedule by tracking actual progress compared to the planned one.
The critical path method according to two experts
We asked two critical path users how best to explain it. This is what they had to say:
"The critical path is just a fancy way of saying, 'How long does each task take to complete the project? Use this information to find out the end date of the project.' When a task takes longer than expected, the end date is pushed back are some tasks that do not immediately affect the project completion date, which may be delayed by some time.
Raquel Burgess, Constructora Capterra
“Some of the activities should take place in parallel. For example, if you try to make a fried breakfast by doing one task at a time and one at a time, things will go wrong. Plates need to be heated while other activities are roasted.” Toasting The sausages are being fried while bacon and sausages are on the grill The eggs should be fried last A critical path analysis is a schematic representation of what needs to be done and when for each Activity and resource can be applied ".
Terenz Jackson, Ph.D and CEO/Managing Partner of WEpiphany LL
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Background and history of the critical path
dr Bennett is no stranger to the critical path. He has applied critical path programming to a variety of projects since 1965. He also spent 29 years at the University of Alaska's Fairbanks College of Engineering, teaching undergraduate and graduate courses in engineering management, including project management and scheduling.
In addition totheir books, has authored more than 50 professional papers and articles on topics ranging from construction management to networking techniques to project planning.
dr Bennett points out that the critical path has come a long way. In fact, the original critical path method was done by hand. like dr Bennett describes:
“The original critical path method used arrows to represent tasks and linked them together, connecting their start and end nodes so that the correct sequence unfolded. This approach persisted for a decade, when another method with the same results became popular. Professor John W. Fondahl, professor of construction management at Stanford University, suggested in a 1961 article that each task should be represented by a node (square, circle, or oval) and the nodes connected by lines or arrows showing the sequence between them represent tasks. This approach, known as Activity-on-Node (AON) or Method-of-Precedence, quickly caught on and replaced the older Activity-on-Arrow (AOA) method in almost all applications.
How the critical path method came about
The use of the critical path method to plan projects began in the late 1950s with two concurrent and independent projects. The US Navy Ballistic Missile Program (Polaris) was behind schedule and needed help solving the problem. The proposed solution was to divide the project into several thousand tasks, represent each task with an arrow, connect the arrows in the correct order, estimate the duration of each task, calculate the duration of the project, and assign the criticality of each task to plan.
Around the same time, EI DuPont de Nemours Company, an American chemical company, was experiencing delays in plant closures, a project to reorganize production facilities for various products. They too needed help and the proposed response was similar to the Polaris program.
The developers of the Polaris program approach called their solution the Project Evaluation and Review Technique (PERT), while the DuPont method was called the Critical Path Method (CPM). Although these methods are similar, they used different techniques to estimate task duration.
The PERT method used three different time estimates for each task duration and calculated the probability of completing the project at a given point in time. DuPont's approach used a time duration for each task; He was not only concerned with the completion time of the project, but also with the analysis of the additional costs that would arise if the project duration were shortened.
dr Bennett says that today "the terms PERT and CPM are used interchangeably, both denoting any network scheduling technique, and PERT has lost its inclusion of three time estimates and probabilities."
The everyday advantage of the critical path
Although it emerged in the late 1950s, the critical path is still incredibly important to project managers today. It provides a visual representation of project activities, clearly presents the time required to complete tasks, and tracks activities so you are not left behind. The critical path method also reduces uncertainty because you have to calculate the shortest and longest time to complete each activity. This forces you to consider unexpected factors that might impact your tasks and reduces the chances of an unexpected surprise popping up during your project.
According to the doctor. Bennett, the critical path method also has three main benefits for project managers:
- Identify the most important tasks:First, it clearly identifies the tasks that you need to accurately manage. If any of the tasks on the critical path take longer than the estimated duration, start later than planned, or finish later than planned, the entire project will be impacted.
- Helps reduce deadlines:Second, "If, after the initial analysis has predicted a completion time, there is an interest in completing the project in a shorter timeframe, then it is clear which task or tasks qualify for a reduction in duration," said Dr. bennett With a critical path methodology displayed as a bar chart similar to a Gantt chart, it's easy to see where tasks are within the overall timeline. You can see the activities on the critical path (they are usually highlighted), as well as the duration of the tasks and their sequences. This provides a new layer of information about your project timeline, giving you more insight into which task durations you can change and which should stay the same.
- Compare plan to actual:And finally says Dr. Bennett that the critical path method can also be used to compare planned progress with actual progress. “As the project progresses, the basic schedule developed from the initial critical path analysis can be used to track schedule progress. During a project, a manager can identify tasks that have already been completed, the expected remaining duration for ongoing tasks, and any planned changes to future task sequences and durations. The result will be an updated schedule that provides a visual way to compare projected versus actual progress compared to the original baseline.”
Experts share the #1 benefit of the critical path
“For me, the biggest advantage of the critical path method is that it makes risk assessment easy. When I've defined dependencies and change plans, it's very easy to say, 'Because you missed the deadline, the next release is coming. .is delayed by X days, and that puts us Y days ahead of schedule.” Simple. However, I don't think you need to fully adopt a method like a critical path to do this in projects. It's best to adopt the parts of the method you have. working for your project and your team - being adaptable as a project manager will help you achieve true success."
Brett Harned,Digital project management consultant, author, speaker and community builder.
“Two issues that continue to plague projects are the conflicting priorities of cross-functional team members and distractions from “noise” in the project. With so much activity, the critical path provides a clear and concise view of what needs to happen next. "Continuance and 'who's on the clock' to meet project commitments".
Robert Kelly, co-founder of@PMChatand managing partner ofKelly solutions, a project management company.
"I particularly like the 'unintended benefits' that critical path (CP) analysis offers, including the discovery of hidden dependencies and resource conflicts. CP analysis also often results in better prioritization and reallocation of team members. Equipment. ."
Jeff Furman, PMP, written by"The Project Management Answer Book"
“The critical path method brings an important level of clarity to your project. It is a visual representation of the fragile balance of your constraints: if any activity on the path is late, your project is late. It's also a great way to determine where to invest resources if the project is delayed.
Cassar Abeid,Moderator von Project Management for the Masses Podcast
Important steps in the critical path method
The critical path method consists of six steps:
Step 1: Enter each activity
Using the work breakdown structure, you must identify each activity (or task) involved in the project. This activity specification list should only contain top-level activities. When detailed activities are used, critical path analysis can become too complex to manage and maintain.
A work breakdown structure divides projects into manageable sections.
The first step is to identify the key deliverables of a project. You can then start breaking down the high-level activities into smaller units of work.
You can choose how you want your work breakdown structure to be displayed. Some people use a tree structure while others use lists or tables. A sketch is one of the easiest ways to represent a work breakdown structure.
Step 2: Create dependencies (Stream of Activities)
Some activities depend on the completion of others. Listing the immediate predecessors of each activity will help you identify the correct order. To correctly identify activities and their priority, starting with Step 1, ask yourself these three questions for each activity on your list:
- What task must be performed before this task can be performed?
- What tasks need to be done concurrently with this task?
- What tasks should be performed immediately after this task?
Step 3 - Draw the network diagram
Once you have identified the activities and their dependencies, you can draw the critical path analysis (CPA) diagram, known as the network diagram. The network chart is a visual representation of the order of your activities based on dependencies.
This critical path diagram used to be hand drawn, but now there are software programs that can create this diagram for you.
Step 4: Estimate the time to complete the activity
Using past experience or the knowledge of an experienced team member, you now need to estimate the time it will take to complete each activity. If you're managing a smaller project, you probably estimate time in days. When working on a complex project, you may need to measure time in weeks.
If you don't want to use your best estimates, you can use the 3-point estimation method, which is designed to put more weight on the most realistic time frame.
Three-point estimation requires you to provide three time estimates for each task, based on past experience or best estimates. The estimation method is presented in formulas to calculate the time duration more precisely.
a = best-case estimate
m = most likely estimate
b = the worst case estimate
These three values characterize what happens in the ideal case, what is most likely and what happens in the worst case.
Once you identify these values, you can use them in two different formulas. The first is used to find the weighted average, which gives more weight to the "most likely" value. The formula is as follows. E stands for estimate, and 4 and 6 represent the default method, which gives more weight to the most realistic value.
mi = (a + 4 m + b) / 6
The second way to use these values is known as the triangular distribution. The main difference is that this method does not give more weight to the Most Likely value. The formula is as follows. E stands for estimation and the 3 stands for the standard method.
mi = (a + m + b)/3
Step 5: Identify the critical path
Now there are two ways to identify the critical path. You can look at your network diagram and easily identify the longest path through the entire network: the longest sequence of activities along the path. Make sure you find the longest path in terms of longest duration in days, not the path with the most frames or nodes.
You can also identify critical activities using the forward pass/backward pass technique by identifying the earliest start and end times and the latest start and end times for each activity.
If you have multiple critical paths, you will encounter sensitivity on the network. A project schedule is considered sensitive when the critical path is expected to change after the project has started. The more critical paths there are in a project, the greater the likelihood of a deadline change.
Step 6 - Refresh the critical path chart to show the progress
As the project progresses, you will learn when the actual activity is complete. The network diagram can then be updated to include this information (instead of continuing to use estimates).
By updating the network diagram as new information becomes available, you can recalculate a different critical path. You'll also have a more realistic view of your project's completion date and can see if you're on track or falling behind.
Other scenarios in the critical path method
One of the greatest benefits of the critical path method is identifying the crucial tasks that, if missed, will impact your project's completion date. It also provides insight into the status of your project so you can see if you're on the right track.
reducing your hours
When following the critical path method, you may want to intentionally shorten the duration of your project or compress the project plan to meet the deadline. There are two ways to do this: fast following or blocking.
In the Quick Track, you look at the critical path and decide which activities can run in parallel to speed up the project. You only need to review the activities on the critical path because all other activities have slack (decreasing the duration of those activities only gives them more slack).
While fast tracking shortens the project schedule, it also poses a risk because you are running activities in parallel that were originally planned sequentially.
The lockout period or lockout refers to the shortest possible period of time that an activity can be scheduled for. It does this by adding more resources to complete that particular activity. However, locking the critical path results in lower quality of work since the goal of lock duration is speed.
Resource Limits Management
While managing your project, you may also encounter resource limitation issues that may change the critical path. If you're trying to plan certain activities at the same time, you may need more people than you have available. Therefore, these activities have to be postponed. Resource leveling is the process of resolving these conflicts.
Resource leveling and expansion
Resource leveling lets you resolve resource allocation conflicts. A resource-level schedule can include delays due to resource shortages (a resource is not available when it is needed).
Resource leveling can also cause a previously shortest path to become the longest or "most resource critical" path. This happens when tasks on the critical path are affected by resource constraints.
A similar concept is called a critical chain, which protects the activity and duration of projects from unexpected delays due to resource shortages.
Final evaluation of the project
These scenarios show all the unexpected changes that can occur while managing a project and how they can affect the critical path. Although things can always change, the good news is that you can measure the deviation from the original project plan and track how it affected the final project.
Flexibility and assessment of delays
Of course, a schedule created using the critical path method will have a lot of variability because you have to use best estimates to calculate the time. If a mistake is made in the activity completion time, the entire critical path schedule may change. Or you may need to intentionally delay project activities due to resource constraints.
Sorting out these delays and identifying the causes can help you avoid similar problems in the future. An important part of your post-project plan is the as-built critical path, which analyzes the specific causes and effects of changes between the planned schedule and the actual implemented schedule. The As-Built Critical Path is a schedule that shows the dates when the activities actually took place and allocates time to determine responsibility for delays in the critical path.
How to use PERT in critical path method
If you recall the history of the critical path method described earlier in this article, you may recall that PERT (Program Evaluation and Review Technique) developed by the Navy in the late 1950s to allow for the faster manufacture of Supporting missiles, a variation of the critical technique is . Route method that takes a more skeptical view of availability estimates.
What is PERT?
The critical path method and PERT are often used in the same contexts and scenarios. Although they are similar, you should understand each concept and its differences.
A PERT chart, or activity arrow chart, is a visual representation of your project timeline, showing the sequence of tasks and which tasks can be completed concurrently. A PERT chart is created using much of the same information used in the critical path method, such as: B. early and late start dates, early and late finish dates, and glides (or glides) between activities.
However, the biggest difference between the critical path method and PERT is the time estimation. The critical path method does not take time variation into account. They use best estimates of completion times and these times are subject to change. With PERT, you place more emphasis on the more realistic completion time.
Critical Path Method and PERT
You can use PERT in your critical path method in step four of the process if you need to estimate activity completion times. The goal of using PERT is to steer time estimates towards the most likely scenario and avoid unrealistic time frames.
To use PERT, you need to estimate the shortest possible time each activity will take, the most likely time, and the longest time it could take if the activity takes longer than expected.
With this information, you can use this formula when you need to estimate the completion times of activities in the critical path method (step four).
Shortest time + 4x likely time + longest time / 6 = expected time to complete the activity
How to find the critical path in a PERT chart
You can identify the critical path in a PERT chart because the chart contains the same information that is needed for the network diagram in the critical path method.
A PERT chart is drawn with circles for each activity, with the name of the activity and the estimated duration on each circle. The arrows represent paths related to the dependencies.
To find the critical path on the PERT chart, first determine how many paths you can follow from start to finish. Then add up the total duration of activities on that path. For example,
Route 1 Duration: 12 days (Task 1 and Task 3)
Route 2 Duration: 11 days (Task 2 and Task 3)
Route 3 duration: 10 days (task 4)
In this case, the critical path is task 1 and task 3 because they take the longest time.
Critical Path Software
When the critical path method was first developed, you had to manually identify the critical path by drawing the network diagram with "nodes" to show the steps of a project and connecting the nodes with arrows or "arcs".
However, drawing nodes, tables, and arrows can be a difficult and time-consuming task, especially when things are constantly changing at the beginning of a project.
Instead of relying on hand-drawn diagrams, there are several project management software programs today that will do the work for you and identify the critical path at the touch of a button.
Here are two different tools with critical path capabilities:
Find the critical path with Microsoft Project
You can view the critical path in the Microsoft Project Gantt Chart view.
First you need to enter all your tasks, their start and end dates, the duration of each task and the predecessors. You can then customize the MS Project file preview to show the critical path.
- CliqueTo see>Gantt chart.
- CliqueFormatand then select thecritical tasksselection box
Tasks on the critical path now have red Gantt bars.
Identify the critical path in other views
You can view the critical path in any task view by highlighting it.
- click noTo seetab and select a visualization in thetask viewsGroup.
- Stay indoorsTo seetab, clickCriticalvonmain emphasisList. The critical path is displayed in yellow.
- To view only the tasks on the critical path, click the buttonFilterArrow and selectCritical.
In a network diagram, tasks on the critical path automatically appear in red. No need to tag.
View the critical path in a master project
Entire sub-projects can be on the critical path when managing a parent project. To identify worksets on the critical path, you can tweak Microsoft Project to treat worksets as summary tasks.
- choosethe planand then scroll down tocalculation options for this project.
make sure, thatProjects entered are billed as summary tasksCheckbox is checked.
Shifting tasks to the critical path
Critical tasks usually have no slack. However, you can instruct Microsoft Project to include tasks that are one or more days late on the critical path so that it can identify potential problems that may arise.
- CliqueProgressive, and then scroll down tocalculation options for this projectArea.
- Add a numberTasks are critical if the distance is less than or equal toCrate.
Identify the critical path in seconds with Smartsheet
Smartsheet, a work management and collaboration tool in spreadsheet design, offers a pre-formatted spreadsheetGantt chart templateto find the critical path even easier.
All you need to do is fill in your own project planning information with this pre-built Gantt chart template with pre-formatted sections, subtasks, and sub-subtasks. A Gantt chart is automatically generated for you and with a click of a button you can identify the critical path in the Gantt chart.
To find the critical path in Smartsheet using a Gantt chart template:
1. Choose a Gantt chart template
- Go to Smartsheet.com and log in to your account (orStart a free 30-day trial).
- Click on the start screencreate a new oneand choosesearch models.
- Type "dependencies" in theSurvey Templatesfield and click the magnifying glass icon.
- ChooseBasic project with Gantt and dependenciesand click on the blue oneuse templatein the upper right corner.
- Give your template a name, choose a save location and click the buttonOKTaste.
2. Enter your task information
A pre-designed formatted template with ready sample content will open for reference. In this section you add your activities or tasks from your work breakdown structure. Here you can also view the hierarchy or relationship between tasks.
The yellow cells above are for guidance only. To remove them, right-click each yellow box and select itdelete a line.
- Add your tasks below thatHomework nameSplit.
- Use the cells labeled Section 1, Section 2, and Section 3 to set the hierarchy (for more information on hierarchies, seeClick here).
- If you need to delete a row, right-click and select the cell of the row you want to deletedelete a line.
On the left side of each row, you can attach files directly to a task or initiate feedback with a colleague on a task to add more context to your project.
3. Enter the start and end dates
Add start and end dates for each task. In the Gantt view, when you click either end of a green task bar and drag it to the right, Smartsheet automatically changes the corresponding dates in the task chart.
- Select a cellStart dateÖfinal dataSplit.
- Click on the calendar icon and select a date.
You can also manually enter a date in the cell. Smartsheet automatically calculates the duration of each task for you.
4. Add % Complete and Assigned to the information
Ö% CompletemiAssigned toColumns provide more context around your project. In the Gantt view on the right, you can quickly see how far along a task is by looking at the length of the thin gray bars within the task bars.
ÖAssigned toIn the column, you can assign the task to a specific team member, which allows you to see who is doing what.
- NO% CompleteIn the column, enter the percentage of work completed for this task. Enter an integer and Smartsheet will automatically fill in the percent sign.
- NOAssigned toColumn, choose a name from the drop-down menu or manually enter a new name.
5. Establish predecessors
Predecessors are used to create dependencies between tasks (identifying which tasks should be completed before or after another task).
- At the far left of the worksheet, each row is assigned a number. insidepredecessorIn the column, enter the row number that represents the previous task row. This creates a link from the current row (the child task) to the specified row (the predecessor task).
- Enter the line numbers of all other predecessors in thepredecessorSplit.
You can also create predecessor dependencies in the Gantt chart on the right. Drag the lower-right corner of a Gantt bar onto the Gantt bar of the task you want to track. EITHERpredecessorThe column is automatically updated.
6. Identify the critical path
Now that you've created a Gantt chart in Smartsheet, you can identify the critical path in the Gantt chart with the click of a button.
- On the right side of the screen where your Gantt chart is displayed, click the rightmost button that represents a critical path (the two red Gantt bars).
- In the Gantt chart, tasks that are on the critical path are highlighted in red.
How to import a Microsoft Project (.MPP) file into Smartsheet
Smartsheet works with Microsoft Project. So if you already have your project planning information stored in Microsoft Project, you can easily import it directly into Smartsheet.
- click nolargeand click the gray Import button.
- Select theImport file from MS Project.
- Click Select, choose the file you want to import and clickOpen.
- CliqueKeep goingIt is aimport settingsthe form appears. Select the row of the form that contains the column headings (this will probably be the first row) and click on itObject.
- The imported file will appear as a new sheet in Smartsheet. Click the worksheet name to open it.
Are you studying for the PMP® exam? This is what you need to know about the critical path method
For Project Management Professionals (PMP)®you must pass the PMP exam, a 200-question multiple-choice test offered by the Project Management Institute (PMI).
The critical path is an important part of the PMP exam and there will certainly be questions about it on the exam. You must be able to draw a network diagram, identify the critical path, apply the pass-forward/pass-back technique and calculate slack.
Here is an overview of the most important things you need to know about the critical path method to help you pass the PMP exam:
How to draw a network diagram
The PMP exam will ask you to draw a network diagram. The check lists all activities in a project and tells you when the activities can start. Using this information, you are prompted to identify the critical path and its duration.
To explain how to draw a network diagram, Bennett created a sample project with eight tasks:
- Design Tank Project (10 days) can start immediately.
- Tank foundation construction (25 days) and tank supplier selection (8 days) can start once the tank design project is completed.
- Manufacture of tank components (10 days) can begin once tank supplier selection is complete.
- The delivery of the tank to the site (4 days) can start as soon as the fabrication of the tank components is completed.
- Preparation of installation drawings (3 days) can begin once tank supplier selection is complete.
- The assembly of the tank (15 days) can begin once the delivery of the tank to the site, the preparation of the installation drawings and the construction of the tank base are completed.
- Tank testing and commissioning (4 days) can begin as soon as tank assembly is complete.
- The project is completed with the test tank and commissioning.
To answer the question you need to draw a network diagram.
To see how:
- Draw a diagram and label it as your first activity (Tank Design Project). Be sure to write the duration in days in the field (in this case it is 10 days).
- Begin your diagram by drawing the relationship between the Design Tank Project, Build Tank Foundation, and Select Tank Supplier. You can do this by drawing a box for the other activities and arrows for those boxes in the Design Tank project.
- Continue drawing boxes to represent activities and arrows to represent when an activity can begin.
After drawing the network diagram, you can find the critical path. Remember, the critical path is the longest path in days across the network, not the path with the most cells.
In this example, the critical path is Design Tank Project, Build Tank Foundation, Assemble Tank, and Test & Commission Tank with a total duration of 54 days.
You can identify the critical path by looking at the chart to find the longest duration in days, or you can use the step forward/step back technique described in the next section.
How to use the forward pass/back pass technique
The Pass Forward/Step Back technique is another way to find the critical path. It is best used when you have multiple branches or multiple entry points to an activity.
You may also need to use the step forward/step back technique when asked to determine the earliest start or end times or the latest start or end times for an activity. Or to find the slack (or float) for any activity.
Before you start using the pass-forward/pass-back technique, you should first understand a few terms:
- Earliest Start Time (ES): The earliest time an activity can begin after the previous dependent activities have completed.
- Earliest Finish Time (EF): The earliest start time of the activity plus the time required to complete the activity (the earliest time an activity can be completed).
- Last Finish Time (LF): The last time an activity can be completed without delaying the entire project.
- Latest Start Time (LS): The latest finish time minus the time required to complete the activity.
As you move forward/backward in your network diagram, order each value according to the legend below (SL stands for Slack, which we'll cover in the next section).
How to do the Forward Pass: Find the earliest start and finish time
There are two formulas in the forward pass/back pass technique. The first is the forward pass formula, which you can use when moving from the beginning to the end (from the first to the last activity) of your network diagram. This formula finds the earliest start time (ES) and earliest end time (EF) for each activity.
To start forwarding, set the first ES task to zero. For all other tasks, the ES is the same as the EF of its immediate predecessor.
Use this formula to calculate EF:
FE = ES + duration
Therefore, for the Design Tank project, the ES is zero and the EF is 10 (10+ duration of 0). We also know that the ES for Select Tank Provider is 10 and the EF is 18 (10 + 8 duration). Continue in this manner throughout the network diagram.
To do the backward pass: Find the last start and end time
The second formula is for stepping back when moving from the last activity to the first activity (you are moving backwards). This formula finds the latest start time (LS) and latest end time (LF) for each activity.
To start the backward pass, make the last LF activities equal to your EF. For all other tasks, the LF corresponds to the LS of its immediate predecessor.
Use this formula to calculate LS:
LS = LF - Duration
For the Test & Commission tank, the LF is 54 and the LS is 50 (54 - duration of 4). For Mount Tank, the LF is also 50 and the LS is 35 (50 - duration 15 days). Continue this formula throughout the network diagram.
To check if it successfully passed backwards, the first activity (Activity A) must have a LS (Last Start Time) of 0.
Here is the complete forward/back pass technique:
Two rules to remember for the forward/back pass
If you encounter overlapping activities (multiple activities feed into one activity) during Forward Pass, you should run the Forward Pass formula for each entry point and use the highest value of the formulas.
If you have activities that are connected during the backward step, you should run the formula for each entry point and use the lowest value.
How to calculate float or slack in PMP exam
After calculating ES and LS for each activity, you can find the gap (or gap).
The slack, also called slack, for an activity is the time between the earliest and latest start time. Critical activities, activities on the critical path, will always have zero float.
There are two formulas for calculating sag based on the values identified in the forward pass/backward pass technique.
Folga = LF-EF
Punch = LS - ES
You must use this process when prompted to identify an activity gap in the PMP exam. If you're not sure which activities are on the critical path, you can find the buffer for each activity, knowing that activities on the critical path always have a zero buffer.
The last figure below shows the release values for each task. You can see that the four tasks on the critical path have no leeway: design the tank layout, build the tank foundation, assemble the tank, and test and commission the tank.
Key terms of critical path for PMP check
These are the key terms related to the critical path method that you need to understand before taking the PMP exam.
- Critical Path Method (CPM):The critical path method is a step-by-step process planning project management technique that identifies critical and non-critical tasks and avoids scheduling issues and process bottlenecks.
- Critical Path DRAG (Devaux Deleted Activity Indicator):The time that an activity on the critical path adds to the project lifetime. Or, alternatively, the amount of time that the project's completion date would be reduced by reducing the duration of an activity on the critical path to zero.
- Criticality Index:The criticality index is used in risk analysis and shows how often a specific task was on the critical path during the analysis. Tasks with a high criticality rating are more likely to cause project delays because they are more on the critical path.
- First start time:The earliest time that an activity can begin after previous dependent activities have completed.
- Premature end:The earliest start time for the activity plus the time required to complete the activity.
- Last end time:The last time an activity can be completed without delaying the entire project.
- Last start time:The latest finish time minus the time required to complete the activity.
- Total turnover:The amount of time that an activity can be delayed from its expected start date without delaying the entire project.
- free float:The amount of time an activity can be deferred without delaying the early start date of a successor activity.
- Fast forward:The process of determining early start or end times for activities in the critical path method.
- iterate again:The process of determining late start or late finish times for activities in the critical path method.
- Network Diagram:A schematic representation of the relationships between project activities, always drawn from left to right to reflect the order of the project.
- Network analysis:The process of breaking down a complex project into components (activities, duration, etc.) and mapping them to show their interdependencies and interrelationships.
The easiest way to find the critical path
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