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Effort and Schedule

Sizing the project by using function points, SLOC, or other methods is a job only half done. Transforming the size to a deliverable effort within a comfortable schedule makes the project planning a complete success story. Further, the total project effort (for example, in person months) that needs to be consumed in a given schedule provides the guidance to do a proper resource loading.

Once the phase-wise resource loading details are available, you can apply the resource rate to each category of resource—such as project manager, architect, analyst, and developer—for the duration of the assignment. Thus the total base cost for the project is calculated. You can then add project management, configuration management, and other overheads as appropriate to get the gross cost. Figure 7.3 shows the broad parameters that are to be taken into account during different lifecycle stages of the project execution.

Figure 7.3

Figure 7.3 Deriving effort and costs.

Deriving Effort

The overall project effort (typically measured in person months) is directly dependent on two critical inputs: application size and project team/programmer productivity. The steps to calculate each of these items are as follows:

  • From the given specification for the application, calculate the size of the application. The size can be estimated by using one of the popular estimation methods, such as
    • Function points method: Output will be in FP count.
    • Object points method: Output will be a list of classes of simple/medium/complex categories.
    • SLOC method: Output will be a "gut feel" of lines of code.
  • Make sure that you have the productivity (delivery rate) available for the technology platform on which the application is being developed. For every language there are available average productivity figures that should be adjusted by the historic project productivity data for your own IT organization. Productivity of your project team:
    • Is based on competency of programmers
    • Is specific to a given technology
    • Is dependent on the software development environment
  • Convert application size to effort (in person months):
    • Effort = Application size x productivity
  • The effort thus derived is the total project effort that would be spent for all the lifecycle stages of the project, from requirements creation through user acceptance. Add project management and configuration management effort as applicable. The effort is also the aggregate of the individual effort spent by each of the resources assigned to the project.

Scheduling

Transforming the overall project effort into a delivery schedule (elapsed time) is somewhat tricky. If the right approach is not applied, the risks of project failure are high. There are three alternatives to calculate the schedule:

  • Use popular scheduling methods like COCOMO II.
  • "Gut feel" scheduling based on past experience.
  • Schedule driven by business user need.

The schedule data that can be obtained by one of these methods is in the form of duration required to deliver the project itself. For example, the schedule could span 10 months from the start date of the project. The schedule thus encompasses all the lifecycle stages of the entire project. From the total duration given to the project team, the project manager must divide the time into lifecycle-based segments. The lifecycle phase percentage is also to be based on historical delivery information of the IT organization. For example, with 10 months of elapsed time, the schedule can be split as follows:

  • Requirements: 2 months (20 percent)
  • Detailed design: 1.5 months (15 percent)
  • Build and unit test: 4 months (40 percent)
  • System and integration test: 2.5 months (25 percent)

Resource Loading

Resource loading is a complex activity and has to be worked on with extreme care. Improper assignment of resources will have an impact on project delivery schedules as well as the quality of outputs. Resource loading requires two critical mapping considerations:

  • The right resource role for the appropriate lifecycle stage. For example, you need to know when to assign a project manager, an architect, or a programmer.
  • The right duration of assignment. This includes when to assign and when to release. The effort spent by each resource is determined by tactful resource allocation method.

For Figure 7.3 shown earlier in this section, the resource loading patterns are displayed illustratively in Table 7.2. For your project, you can prepare a table showing resource role assignments for the appropriate durations. For example, assume a total project effort of 100 person months. This effort includes project management and configuration management effort. Table 7.2 illustrates the typical resource loading based on the percentage breakup of elapsed time, as given in the example in this chapter.

Table 7.2. Resource Loading Chart

Resource

M1

M2

M3

M4

M5

M6

M7

M8

M9

M10

Total PM

Project manager

1

1

1

1

1

1

1

1

1

1

10

Technical analyst

1

1

1

1

1

5

Business analyst

2

3

3

3

3

3

3

3

2

2

27

Programmer

4

4

6

8

10

8

6

4

50

Configuration controller

1

1

1

1

1

1

1

1

8

Total effort

3

5

10

10

11

13

15

14

11

8

100

[M1 = Month 1] [Total PM = Total Person Months].

Costing

Once the resource loading chart (as shown in Table 7.2) is complete, it is fairly easy to attach the rate per hour (or rate per week/month) for each of the resource roles, such as project manager, architect, analyst, developer, etc. The steps are

  • Arrive at the rate per time unit for each of the resources.
  • From the resource loading chart, obtain the duration of assignment for each category of resource (project manager, architect, analyst, developer).
  • Multiply the individual resource allocation duration by the rate to obtain individual resource costs.
  • Aggregate the individual costs to get the overall project cost for resources.
  • Add overheads and buffers as applicable.
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