Time Scheduling – Project Management Ver 1.0
Release
1st
January 2009
Prepared By
K.V.Sajesh Nambiar (Software
Head, Sr. Asst. Vice President)
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Time
Management document for software Projects
1. Work
Breakdown Structure (WBS)
A work breakdown structure is a tool and techniques used to decompose project scope components into smaller and more manageable components or work packages. The project manager creates it with project team members, and it has many purposes. First, the WBS helps to identify the major deliverables of the project. It creates s total view of the project in small, manageable components and, finally, the WBS helps create a common understanding of the project deliverables.
WBS is composed of two elements :
a. Level of Work (which is of three levels)
a. Highest level à Project Name of Major Task
b. Intermediate level à summary tasks
c. Lowest level à work task
b. Unique number identifier
1.1 Creating a WBS
- Use Tree structure
- Determine how many levels of decomposition appropriate in the project
- Determine how the levels will be organized
- Label level 1 the project name
- At level two, decompose the project into set of deliverables
- For each subsequent level, decompose the project into smaller components
- Create the lowest level of decomposition. This level, called work package should be small enough to easily assign to one person to complete. You also will be able to easily create time and cost estimates for this level.
- Create unique numeric identifier for each component on the WBS, and should starts from the left side of the WBS and works the same as numeric outline (e.g 1.0, 1.1, 1.1.1 etc.).
2. Activity
Sequencing
This is a time management planning process used to determine how the work of the project will progress. In other words it is the sequence of the task of the project. In activity sequencing you take the activity list created by the work breakdown structure, then use the tools and techniques to decide on the progression of the work, which results in the creation of a network diagram.
2.1
Components
of Activity sequencing
2.1.1 Activity List
Lowest level of WBS is work package and it is also called as activity list.
2.1.2 Dependencies
A dependency describes the relationship between two tasks. There are three types
2.1.2.1 Mandatory dependencies
Are inherent in the work to be done
2.1.2.2 Discretionary dependencies
Created by the project team
2.1.2.3 External dependencies
Come from outside of your project
2.1.2.4 Two common methods are using for activity sequencing, ie. Precedence diagramming method (PDM) also known as Activity On node (AON) and other method is Activity On Arrow (AOA). We have to follow AON. Here Boxes depict the task and arrows depicts the dependency. The four type of relationships are there
2.1.2.4.1 Finish to Start (Activity B cannot start until Activity A is completed )
2.1.2.4.2 Start to Finish (Activity B cannot finish until Activity A has started )
2.1.2.4.3 Finish to Finish (Activity B cannot start until Activity A is completed )
2.1.2.4.4 Start to Start (Activity B cannot start until Activity A is completed )
2.2
Network
Diagram
3. Estimating
Duration Activity
There are 4 types of techniques to determine the duration estimates
a. Expert judgment : Ask the people who will perform the task to provide the estimates
b. Analogous or top-down estimating : Find similar tasks that where performed before
and use the historical data to create the estimates.
c. Quantitatively bases estimating : Unit of work multiplied by the productivity of the
worker.
d. Reserve time or contingency estimating : Reserve time is a unit of measure that is added to original estimate to allow for any schedule risk. The unit of measure can weither be more hours or percentage.
4. Calculating
Critical Path
Critical path is defined as the longest path through the project and has no float, or slack time – meaning the amount of time you can delay the early start of the project without affecting the planned finish date of the project. If a task on critical path slips, the end date of the project slips. To determine the critical path of your project, you use a mathematical analysis tool and technique of the schedule development process called Critical Path Method (CPM).
CPM calculates a single critical path for the project. It requires that you perform a forward pass, backward pass, and calculate float for the entire network diagram.
4.1 Calculating Forward Pass
Start from the earliest point of network diagram. Take the earliest activity and take it as early start and add duration to find out early finish.
|
Early Start |
Early Finish |
|
|
A |
0 |
3 |
|
B |
3 |
8 |
|
C |
3 |
13 |
|
D |
13 |
20 |
4.2 Calculating Backward Pass
Start from the latest point of the network diagram. Take early finish date as late finish date. Subtract the duration from the late finish for getting late start.
|
Activity |
Late Start |
Late Finish |
|
D |
13 |
20 |
|
C |
3 |
13 |
|
B |
8 |
13 |
|
A |
0 |
3 |
4.3 Calculating Float
Calculate float by subtracting early start from late start or early finish from late finish.
|
Activity |
Float |
|
A |
0 |
|
B |
5 |
|
C |
0 |
|
D |
0 |
4.4 Using Critical Path Method
Decide the critical path by looking into the zero float path (pink colour).
5. Calculating
PERT
Program Evaluation and Review Technique (PERT) is like CPM focus on determine the project ‘s duration, but it uses expected calues or weighted averages to perform calculations instead of most likely duration estimation like CPM. PERT mostly relies on mathematics of probability and statistical bell curves.
Three types of estimates are using to do PERT calculation :
- Optimistic : If everything goes well, how long the task will take
- Pessimistic : If everything goes poorly, how long the task will take
- Most Likely : The original estimate provided. Sometimes called a best guess.
5.1 Add values of three estimates to activities
|
Activity |
Most likely |
Optimistic |
Pessimistic |
|
A |
3 |
2 |
5 |
|
B |
5 |
4 |
8 |
|
C |
10 |
7 |
15 |
|
D |
7 |
5 |
10 |
5.2 Determine the mean of the task. Formula for this calculation is :
Mean = (Optimistic + (4* Most Likely) + Pessimistic) /6
|
Activity |
Most likely |
Optimistic |
Pessimistic |
Mean |
|
A |
3 |
2 |
5 |
3.2 |
|
B |
5 |
4 |
8 |
5.3 |
|
C |
10 |
7 |
15 |
10.3 |
|
D |
7 |
5 |
10 |
7.2 |
5.3 Determine the mean standard deviation. Formula for this calculation is :
Standard Deviation = (Pessimistic - Optimistic) /6
|
Activity |
Most likely |
Optimistic |
Pessimistic |
Mean |
SD |
|
A |
3 |
2 |
5 |
3.2 |
.5 |
|
B |
5 |
4 |
8 |
5.3 |
.7 |
|
C |
10 |
7 |
15 |
10.3 |
1.3 |
|
D |
7 |
5 |
10 |
7.2 |
.8 |
5.4 Determine the confidence level you want to achieve. Add the mean to a standard factor multiplied by standard deviation.
Standard Factors and
formulas for each confidence level
|
Confidence Level |
Standard Factor |
Formula |
|
50% |
0 |
Mean |
|
60% |
.25 |
Mean + (.25*SD) |
|
70% |
.53 |
Mean + (.53*SD) |
|
80% |
.84 |
Mean + (.84*SD) |
|
90% |
1.28 |
Mean + (1.28*SD) |
|
95% |
1.65 |
Mean + (1.65*SD) |
|
99% |
2.33 |
Mean + (2.33*SD) |
Using 99% confidence the PERT calculation is given below :
|
Activity |
Most likely |
Optimistic |
Pessimistic |
Mean |
SD |
New |
|
A |
3 |
2 |
5 |
3.2 |
.5 |
4.5 |
|
B |
5 |
4 |
8 |
5.3 |
.7 |
7 |
|
C |
10 |
7 |
15 |
10.3 |
1.3 |
13.5 |
|
D |
7 |
5 |
10 |
7.2 |
.8 |
9 |
Is the technique to reduce the predefined duration of the project. It is of two types :
6.1 Crashing
In crashing you analyze the critical path and determine what you can do to shorten it. It can made possible by
- Add more resource to shorten the task duration
- Reduce scope of the project and subsequently critical path
- Find different way of sequencing of process.
6.2 Fast Tracking
Here you look for tasks worked in parallel instead of sequentially.
7.
Creating
Gantt charts (Bar charts)
Determine the time scale on the X axis and major tasks on the Y axis. Then draw the chart according to the position of the values.
8.
Controlling
Schedule changes
There are three steps by which you keep schedule from changing.
· Plan for change
o Who can request a change?
o How will you determine the impact of the changes to the schedule?
o Is there specific form for requesting a change?
o Who can approve the change?
o What is the reason for the change?
o Is the change is denied, how is the requestor notified?
o What are the advantages and disadvantages for allowing the change?
o If the change is approved, how is the schedule updated?
o Will the change be logged and tracked?
o If the change is approved, how are the tean abd the requester notified?
o Who will review the change?
· Determine whether the schedule has changed
o What you planned on doing (Original schedule)
§ Baseline is the copy of the schedule
o Where you currently are in the process
§ Report % complete on a task
§ Report the time spent on task
§ Report the time spent and time remaining on a task.
o The variance between two.
§ Late starts and late finishes
§ Remaining work
§ Completion date
· Manage the changes
o Requested changes to your project
o Variances to schedule completion
__________