Constructive Cost Model (COCOMO Model), Slides of Software Project Management

Download Constructive Cost Model (COCOMO Model) and more Slides Software Project Management in PDF only on Docsity!

Software effort estimation

COCOMO Model

Presented By:

Kabeer Afzal Khan (SP17-BCS-025)

Abdul Hannan (SP17-BCS-001)

Malik Mohammad Saad (SP17-BCS-009)

Aadil Ahmed (SP17-BCS-022)

Faraz Khan (SP17-BCS-003)

What we Cover in this presentation?

 What is COCOMO Model? Why we this model? How it will be useful in

software project? Explanation about COCOMO-II model?

 Classes of COCOMO Model where it be applied on software project?

 Sub-models of COCOMO 81 and COCOMO II.

 Pros and Cons of COCOMO Model.

History of COCOMO:  (^) COCOMO was first published in 1981 Barry W. Boehm's Book Software engineering economics.  (^) It drew on a study of 61 projects.  (^) This model is typically called COCOMO 81.  (^) In 1995 COCOMO II was developed and finally published in 2000 in the book Software Cost Estimation with COCOMO II.  (^) COCOMO II was tuned using a larger database of 161 projects.

Why COCOMO-II Model?

 Firstly, the need for the new model came as software development

technology moved from mainframe and overnight batch processing to

desktop development.

 Secondly, code reusability, and the use of off-the-shelf software

components.

Development Modes where COCOMO applied on software project  (^) Organic Mode.  Semi-detached Mode.  Embedded Mode.

Modes Continue…..

Property Organic Mode Semi-Detached

Mode

Embedded

Mode

Size 2-50kLOC 50-300kLOC Above 300kLOC

Team Size Small Team Medium Team Large Team

Developer

Experience

Experienced

Developer

required

Average

Experienced

Developer

required

Very Little

previous

experienced

related project

Environment Familiar

Environment

Less Familiar

Environment

Significant

Environment

Innovation Little Medium Major

Deadline Less Tight Medium Tight

Sub-models of COCOMO-81 Model  (^) Basic COCOMO Model.  Intermediate COCOMO Model.  Detailed COCOMO Model.

Basic COCOMO Model:  (^) The first level, Basic COCOMO can be used for quick and slightly rough calculations of Software Costs.  (^) It also useful for short and medium sized software.  (^) The following expressions give the basic COCOMO estimation model: E =a(KLOC)b D =c(E)d People Required =E/D Where:  (^) KLOC stands for Kilo-Lines of code and a, b, c, d are coefficient constant.  (^) E is the total effort required to develop the software product, expressed in person months (PMs).  (^) D is the development time , that is expressed in months.

Example of Basic COCOMO Model:  (^) Suppose a project was estimated to be 40 KLOC. Calculate the effort and development time for organic mode.

Problem Solution:

E=a(KLOC) ^b PM D=c(E)^d months Estimated Size of project= 40 KLOC Organic Mode: E = 2.4 * (40)^1.05 = 115.44 PM D = 2.5 * (115.44)^0.38=15.19 months

Intermediate Model:  (^) As we see basic model was quick but inaccurate and phase insensitive. Intermediate COCOMO model is an extension of basic COCOMO model.  (^) Intermediate model increases the efficiency of prediction through includes the set of 15 additional predicators i.e.,(Cost Drivers) because the basic COCOMO model considers that the effort is only a function of the number of lines of code and some constants calculated according to the various software systems. The Cost Drivers divides into four Categories.  (^) Product Attributes:  (^) Required software reliability extent.  (^) Size of the application database.  (^) The complexity of the product.

 Hardware attributes:

 (^) Run-time performance constraint.  (^) Memory constraints.  (^) The volatility of the virtual machine environment.  (^) Required turnabout time.

Example of Intermediate COCOMO Model:  (^) Example: For a given project was estimated with a size of 300 KLOC. Calculate the Effort, Scheduled time for development by considering developer having high application experience and very low experience in programming.  (^) Solution: Given the estimated size of the project is: 300 KLOC Developer having highly application experience: 0.82 (as per above table) Developer having very low experience in programming: 1.14(as per above table) EAF = 0.821.14 = 0.9348. Effort (E) = a(KLOC)b^ EAF = 3.0(300)1.12^ 0.9348 = 1668.07 MM. Scheduled Time (D) = c(E)d^ = 2.5*(1668.07)0.35^ = 33.55 Months(M).

Detailed COCOMO Model:  (^) Detailed COCOMO incorporates all characteristics of the intermediate version with an assessment of the cost driver’s impact on each step of the software engineering process. The detailed model uses different effort multipliers for each cost driver attribute. In detailed COCOMO, the whole software is divided into different modules and then we apply COCOMO in different modules to estimate effort and then sum the effort.  (^) The Six phases of detailed COCOMO are:  (^) Planning and requirements  (^) System design  (^) Detailed design  (^) Module code and test  (^) Integration and test  (^) Cost Constructive model  (^) The effort is calculated as a function of program size and a set of cost drivers are given according to each phase of the software.