Difference Between Organic, Semi-Detached and Embedded Modes in COCOMO Model

Pre-requisites: COCOMO Model

Software is a program or set of programs containing instructions that provide desired functionality. And Engineering is the process of designing and building something that serves a particular purpose and finds a cost-effective solution to problems. 

Cocomo (Constructive Cost Model) is a regression model based on LOC, i.e number of Lines of Code. It is a procedural cost estimate model for software projects and is often used as a process of reliably predicting the various parameters associated with making a project such as size, effort, cost, time, and quality. 

Features of COCOMO Model

• It is a software cost estimation model.
• It estimates the cost of the software in a rough and quick manner.
• It is mostly used for small-medium sized softwares.
• Basic cocomo model consists of three modes of development-
  • Organic mode
  • Semi-Detached mode
  • Embedded mode

Difference between Organic, Semi-Detached and Embedded Modes

Parameters	Organic	Semi-Detached	Embedded
Software Size	2 to 50 KLOC	50 to 300 KLOC	300 and above KLOC
Team Size	small team size	medium team size	large team size
Developer Experience	experienced developers needed	average experienced devlopers needed	very little experience required
Environment	Familiar environment (known constraints)	Less familiar (some constraints are unknown).	significant environment changes (most of the constraints are unknown).
Innovation	very little innovation is required.	medium innovation is required.	major amount of innovation is required.
Deadline	flexible deadlines.	little bit medium and little bit tight(fixed) deadlines.	deadlines are rigid(not flexible) in nature.
examples	Payroll systems, etc.	utility systems like compiler, operating systems, etc.	complex systems like Air Traffic Monitoring System, Banking software, etc.

Basic Cocomo Model Equations

Effort = a × (KLOC)b , unit=person-months
Development Time = c × (Effort)d , unit=months
Average Staff Size = (Effort) / (Development Time), unit=persons
Productivity = (KLOC) / (Effort) , unit = kloc/person-month

Example

Suppose that a Basic project was estimated to be 400 KLOC (kilo lines of code). Calculate effort and time for each of the three modes of development. All the constants value provided in the following table:

Mode	a	b	c	d
organic	2.4	1.05	2.5	0.38
semi-detached	3.0	1.12	2.5	0.35
Embedded	3.6	1.20	2.5	0.32

Solution

1. for organic mode, 
   • effort = 2.4 × (400)^1.05  ≈ 1295 person-month.
   • dev. time = 2.5 × (1295)^0.38 ≈ 38 months.
2. for semi-detach mode, 
   • effort = 3 × (400)^1.12  ≈ 2462 person-month.
   • dev. time = 2.5 × (2462)^0.35 ≈  38 months.
3. for Embedded mode, 
   • effort = 3.6 × (400)^1.20  ≈ 4772 person-month.
   • dev. time = 2.5 × (4772)^0.32 ≈ 38 months.