AIB Method (Activity In Box Method)
AIB Method (Activity In Box Method) is the best and one of the most popular methods project managers use when building a network diagram.
The good thing about using a tool like Microsoft Project is that it makes it easy to build a network diagram. The bad thing about the tool is that it makes it so easy; project managers don’t always understand what they are doing. They just plug in the activities and move on.
Every project manager should know how to build an AIB manually so that he or she really understands the concepts before working in Microsoft Project. The project managers who understand it are much more effective and know how to use the tools more effectively. Those who do not know how to build a schedule manually often make mistakes and negatively impact a project’s triple constraints.
You will conduct a forward pass through a network to determine the early start and early finish of each activity. When you complete the forward pass, you know which activity will be the last one to complete. The Early Finish for that activity is the earliest date that your project can complete. Next, you will conduct a backward pass to determine the late start and late finish for each activity. Last of all, you calculate the slack/float for each activity.
Let’s define a few terms:
• Critical Path (CP) – by definition, it is the path of activities that all have a slack/float of 0. This path is especially important because if any of them complete later than scheduled, your project may not complete on time.
• Early Start (ES) – is the EARLIEST time the activity could possibly start.
• Early Finish (EF) – is the EARLIEST time the activity could possibly finish.
• Late Start (LS) – is the LATEST time the activity can start and not jeopardize the scheduled completion of the project.
• Late Finish (LF) – is the LATEST time the activity can finish and not jeopardize the scheduled completion of the project.
• Slack/Float – is calculated by: LF – EF, or LS – ES (both formulas will result in the same answer; if not, one of your numbers is incorrect). The slack/float tells you the number of days/weeks/months that an activity can begin late, or the number of extra days/weeks/months that an activity can take without impacting the completion time of the project. However, this time is shared by all of the activities on a path. If you use up all of your slack on an activity at the beginning of a path, subsequent activities will have less slack or no slack.
Resource Constrained Planning
Once a project schedule established, we need to align the appropriate resources to accomplish the work. As resources are applied, conflicts may arise if resources become over-allocated.
A project manager can address resource conflicts in a variety of ways, but the first step is to realize there is a conflict. If the project team builds a schedule using a scheduling tool like Microsoft Project, the PM can run an ‘Overallocated Resources’ report.
Once the over allocation is identified, there are several key strategies to address them:
(1) Resource leveling
(2) Adding or modifying resources
(3) Changing the project
Most methods for addressing resource conflicts cost the project something, either more money, less functionality, or an extension in the scheduled completion.
In some cases, we have no choice – operational necessity. For instance, if the company has two bulldozers, and you need four on a particular week, you will have to address that resource conflict to complete both projects.
On other projects, resource conflicts take the form of people being over allocated. Ultimately, it will result in personnel turnover.
Addressing resource conflicts improves morale, which increases quality, reduces defects, reduces re-work, decreases team turnover, and increases team commitment.
Resource leveling is easy to do if you are using an automated scheduling tool like Microsoft Project. You can also use the tool to try various what-ifs.
For example, try plugging in new resources and see if their addition will change your scheduled completion time. If they are not working on a task on the critical path, their work will not even affect the project’s scheduled completion.
This method smoothes out the peaks and valleys in the schedule without increasing the overall budget and ff you choose a level only within available slack as an option when you level the resources, leveling the resources will not extend your project’s schedule either. However, if there is not enough slack in the schedule, it will not correct all of your allocation problems, in which case, you will have to use another method to relieve the problem.
In summary, the benefits of resource leveling are:
1. Minimizes period-by-period variations by shifting tasks within their slack
2. Utilizes resources more efficiently
3. Resources do not have days with no work scheduled and other days with too much work
4. Does not increase budget
5. Does not have to change scheduled completion
Adding or Modifying Resources
Adding people to a project must be approached carefully. Additional people are easier to absorb into projects that are well-documented. Adding personnel to well-defined tasks is straightforward when the plan is clear. Throwing people at projects that are in trouble, behind, and already managed poorly often results in an even bigger problem.
Adding resources increases the budget and rarely doubles the work completed. This is because additional people must be trained, which ties up their time and the time of a team member who is training them, and adds to the communication channels.
Modifying resources can take several forms: Assign a person with greater expertise or more experience to perform or help with the activity, and increase productivity through improved methods or technology.
There are three different types of dependencies, including:
Mandatory – requires the completion of another task.
Discretionary – a best practice or convenience. However, the subsequent task can begin if the discretionary dependency is not completed.
Why a Critical path is important to a project?
The critical path is the path of activities that all have a slack/float of 0. It is important because if any of them complete later than scheduled, the project may not be completed on time.
Float is the number of extra days/weeks/months an activity can take without impacting the completion time of the project. It is calculated by subtract Earliest Finish Time (EF) from Latest Finish Time (LF).
An activity duration estimate
The duration estimate for an activity is the time required to perform the work plus any associated waiting time.
Benefits of resource leveling
• Minimizes period-by-period variations by shifting tasks within their slack
• Utilizes resources more efficiently
• Resources do not have days with no work scheduled and other days with too much work.
• Does not increase budget
• Does not have to change scheduled completion