Chapter 27. How Program Size Affects Construction

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Contents

• Communication and Size page 650

• Range of Project Sizes page 651

• Effect of Project Size on Errors page 651

• Effect of Project Size on Productivity page 653

• Effect of Project Size on Development Activities page 654

Related Topics

• Prerequisites to construction: Chapter 3

• Determining the kind of software you're working on: Section 3.2

• Managing construction: Chapter 28

Scaling up in software development isn't a simple matter of taking a small project and making each part of it bigger. Suppose you wrote the 25,000-line Gigatron software package in 20 staff-months and found 500 errors in field testing. Suppose Gigatron 1.0 is successful, as is Gigatron 2.0, and you start work on the Gigatron Deluxe, a greatly enhanced version of the program that's expected to be 250,000 lines of code.

Even though it's 10 times as large as the original Gigatron, the Gigatron Deluxe won't take 10 times the effort to develop; it'll take 30 times the effort. Moreover, 30 times the total effort doesn't imply 30 times as much construction. It probably implies 25 times as much construction and 40 times as much architecture and system testing. You won't have 10 times as many errors either; you'll have 15 times as many or more.

If you've been accustomed to working on small projects, your first medium-to-large project can rage riotously out of control, becoming an uncontrollable beast instead of the pleasant success you had envisioned. This chapter tells you what kind of beast to expect and where to find the whip and chair to tame it. In contrast, if you're accustomed to working on large projects, you might use approaches that are too formal on a small project. This chapter describes how you can economize to keep a small project from toppling under the weight of its own overhead.