EME04 Software effort estimation

Software effort estimation

introduction

• Delay estimation until late in the project

• Base estimates on similar projects that have already been completed

• Use one or more empirical models for software cost and effort estimation (Decomposition)

• Use relatively simple decomposition techniques to generate project cost and effort estimates （LOC or FP）

the form

E = A + B × (𝑒_𝑣) ^𝐶

Where A, B, and C are empirically derived constants,

E is effort in person-months,

𝑒_𝑣 is the estimation variable (either LOC or FP)

d = f(𝑣_𝑖)

where d is one of a number of estimated values (e.g., effort, cost, project duration)

𝑣_𝑖 are selected independent parameters (e.g., estimated lines of code)

Decomposition approach

• Decomposition of the problem.

• Decomposition of the process.

Software Sizing

Software size refers to a quantifiable outcome of the software project.

• If a direct approach is taken, size can be measured in lines of code (LOC).

• If an indirect approach is chosen, size is represented as function points (FP).

FP-Based Estimation

focuses on information domain values:

inputs, outputs, inquiries, files and external interfaces

e.g.
FP_estimated = count total × [0.65 + 0.01 × Σ(𝐹𝑖)]

Σ(𝐹𝑖): weighting factors is scored with a value between 0 (not important) and 5 (very important)

Process-Based Estimation