Becoming More Accurate with Reuse

We can get more accurate if we are willing to look more closely at the process and the reuse characteristics. Returning to our example, the first step is to examine the process and then determine the percent of the total effort expended in each step in the development of new code.

Suppose that we know that our organization spends 18% of its time in requirements, 25% in design, 25% in code and test, and 32% in integration (there are only four life cycle phases in this example).

As shown in Table 10-18, new code will require that every bit of that effort must be expended. However, modified and reused code will require less effort.

Instead of 100%, let's say that modified code requires only 20% of requirements effort, and reused code requires only 10%.

Instead of 100% of design effort, we'll say that only 40% will be required for modified software and no design (0%) is required for reused software. The 40% is because we may have to plan how to test the modified software, and maybe we must design the rest of the software in a special way. The value of pure reuse begins to become apparent.

Instead of 100% of the coding and unit testing effort required for new software, modified software requires only 70%, and, again, reused software is essentially "free." For only "pure" reused code will this be zero. If just one single line of code is changed, then it has been modified.

Integration effort doesn't get a break, even with modified or reused code. Even for pure reused code, integration often requires 50%-100%.

For each phase of the process, the effect of reuse can be determined after the percent of effort for each reuse category is determined. Table 10-18 shows that inclusion of reused and modified code wherever possible is indeed a size, effort, schedule, and cost savings.

Table 10-18. Applying an Accurate Estimating Methoc

Process Step

Requirements

Design

Code

Integration

Percent

18%

25%

25%

32%

Delivered

Equivalent

2,138

New

100%

100%

100%

100%

2,138

1,782

Modified

20%

40%

70%

100%

1,124

1,201

Reused

10%

0%

0%

100%

406

5,121

3,668

to Reused and Modified Code

Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

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