Effort Estimation via cocomo

COCOMO is an effort estimation tool introduced by Barry Boehm (Boehm 84). Boehm defined a hierarchy of models: basic, intermediate, and advanced. The basic COCOMO Model is a static single-valued model that calculates development effort and cost as a function of the estimated SLOC. The intermediate COCOMO Model calculates development effort and cost as a function of program size in terms of estimated SLOC and a subjective assessment of several system attributes. The advanced COCOMO Model includes all intermediate features plus an assessment of cost driver's impact on each phase of the system life cycle. COSMOS is based on the intermediate COCOMO Model.

COCOMO delineates software projects into three modes: organic, semi-detached, and embedded. Organic mode is used to describe small, simple projects where the requirements do not require strict adherence. Semi-detached mode describes intermediate size projects with requirements that identify some rigid constraints. Embedded mode describes a software project with requirements containing very strict hardware, software, and operational constraints.

The COCOMO Model calculates person months and project duration using estimated SLOC and the effort adjustment factor (EAF) derived from 15 cost driver attributes. The cost drivers are grouped into four major categories: product, hardware, personnel, and project attributes. Each of the attributes is rated on influence on project complexity using a 6-point basis that ranges from very low to extra high (not all ratings are allowed for all attributes). Based on the rating, the corresponding effort multiplier of each cost driver is used to compute the EAF. More information about the cost driver attributes is located in theCOSMOS Technical Reference(see COCOMO Complexity Influence Assignments).

Product Attributes

These are attributes of the software product you are to develop.

Attribute	Description
Required Software Reliability	The degree to which software errors can be tolerated. The range for poor reliability can be from a slight inconvenience to risk to human life
Size of Application Database	The ratio of the data storage to the program size
Complexity of Product	The degree of complexity in the application's functions; Simple functions have simple expressions in the computational operations, very little nesting in the control operations, and the data management operations consist of simple arrays in main memory; Complex functions have highly nested control operations, difficult mathematical computations, dynamic data relationships in the data storage, and micro-coding for device-dependent operations

Hardware Attributes

These are attributes of the hardware platform you are working with.

Attribute	Description
Time	The measurement of time required for user feedback
Run-Time Performance Constraints	The measurement of use of available execution time
Memory Constraints	The measurement of use of available storage space
Virtual Machine Volatility	The amount of change to the application's environment such as the operating system and hardware upgrades
Required Turnaround Time	The measurement of time required for user feedback