COCOMO Model: Estimating Software Development Effort and Schedule

Learn about the Constructive Cost Model (COCOMO) for software cost estimation. This guide explains COCOMO's different levels (basic, intermediate, detailed), the parameters used for estimation (KLOC, effort multipliers), and how it helps project managers plan resources and schedules effectively.

COCOMO Model for Software Cost Estimation

Introduction to the COCOMO Model

The Constructive Cost Model (COCOMO), proposed by Barry Boehm in 1981, is a widely used software cost estimation model. It estimates the effort and schedule required for software development based on the software's size (expressed in thousands of delivered lines of code, KDLOC). COCOMO helps project managers estimate resources, plan schedules, and make informed decisions in the early stages of software development.

COCOMO Estimation Steps

1. Initial Effort Estimate: Estimate initial effort based on KDLOC using a simple formula (E_i = a * (KDLOC)^b).
2. Determine Cost Drivers: Identify 15 cost drivers (attributes of the project) that influence effort and schedule.
3. Calculate Effort: Multiply the initial estimate by the cost driver factors to get a refined effort estimate.
4. Calculate Development Time: Use a formula to estimate the development time based on the effort estimate.

Project Categorization in COCOMO

COCOMO categorizes projects into three types based on complexity and characteristics:

• Organic: Small, well-understood projects with experienced developers (e.g., simple business systems).
• Semi-detached: Medium-sized projects with a mix of experienced and inexperienced developers (e.g., new operating systems).
• Embedded: Complex projects with stringent requirements and tight coupling to hardware (e.g., air traffic control systems).

COCOMO Models: Basic, Intermediate, and Detailed

Boehm describes three levels of COCOMO models:

1. Basic COCOMO Model

Provides a simple estimate of effort and development time based on the software size (KLOC).

Formulas:

• Effort = a₁ * (KLOC)^a₂ PM
• T_dev = b₁ * (Effort)^b₂ Months

(The values of a₁, a₂, b₁, and b₂ vary depending on the project type—organic, semi-detached, embedded.)

(Graphs showing the relationship between effort/development time and software size for the basic COCOMO model would be included here.)

2. Intermediate COCOMO Model

Refines the basic COCOMO estimates by incorporating 15 cost drivers that reflect various project attributes (product, hardware, personnel, and project attributes). These factors influence the project’s complexity and therefore the effort and time required.

(A table listing the 15 cost drivers and their impact would be included here.)

The intermediate COCOMO equation is:

Effort = a_i * (KLOC)^b_i * EAF

(The values of a_i and b_i and how the Effort Adjustment Factor (EAF) is calculated would be included here. The provided text cuts off before providing this information. This information would be included in the HTML.)

3. Detailed COCOMO Model

(Further explanation of the detailed COCOMO model, which further refines the estimates by considering even more detailed factors, would be included here.)

(Examples demonstrating how to use the basic COCOMO model to calculate effort and development time for different project types and sizes would be included here.)

COCOMO Model: A Detailed Look at Software Cost Estimation

Introduction to COCOMO Models

The COCOMO (Constructive Cost Model) is a widely used software cost estimation model. It helps predict the effort and time required for software development based on project size (in thousands of delivered lines of code, KDLOC). COCOMO offers different levels of detail (basic, intermediate, detailed), allowing you to choose the level of accuracy that suits your needs. The basic model provides a simple estimate, while the detailed model incorporates many factors that can affect a project's cost and schedule.

Basic COCOMO Model

The basic COCOMO model provides a straightforward estimate of effort and development time based on the project’s size (KLOC). The model uses separate formulas for organic, semi-detached, and embedded projects:

(Graphs illustrating the relationship between effort/development time and project size for the basic COCOMO model would be included here.)

Intermediate COCOMO Model

The intermediate COCOMO model refines the basic model by incorporating 15 cost drivers, reflecting various aspects of the software development process (product attributes, hardware attributes, personnel attributes, and project attributes). These cost drivers are multiplied by the basic effort estimate to obtain a more refined estimate.

(A table listing the 15 cost drivers would be included here.)

The intermediate COCOMO equation is:

Effort = a_i * (KLOC)^b_i * EAF

(The values for a_i and b_i for organic, semi-detached, and embedded projects, and an explanation of the Effort Adjustment Factor (EAF), would be added here. The provided text cuts off before fully describing the intermediate COCOMO model.)

Detailed COCOMO Model

The detailed COCOMO model further refines the estimation by applying effort multipliers to each cost driver for each phase of the software development lifecycle (planning, design, implementation, testing, etc.). It breaks down the project into modules, estimating effort for each module individually and then summing these estimates. (Further explanation of the detailed COCOMO model and its six phases would be included here.)