---
title: "COCOMO"
subject: "ICT Project Management"
chapter: 15
key: "semester_7/ict_project_management:cocomo"
source: https://www.bctengineer.com/q/semester_7/ict_project_management/cocomo
site: BCT Engineering
---

# COCOMO

ICT Project Management · Chapter 15: Balanced scorecard and ICT project management

- Asked in: year not given
- Video: [25  COCOMO Detailed](https://www.youtube.com/watch?v=gzgf06bKajs) — Shruti Yagnik
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/ict_project_management/cocomo
- Whole chapter: https://www.bctengineer.com/md/semester_7/ict_project_management/chapter-15

## Question

Explain COCOMO.

## Short answer

COCOMO is an algorithmic cost estimation model that computes effort, development time, and staffing from software size in KLOC and project mode. For a 50 KLOC organic project, using formulas E=2.4×KLOC^1.05 and D=2.5×E^0.38, effort is about 146 person-months, time 16.6 months, needing about 9 people.

## Answer

**COCOMO (Constructive Cost Model)** is an algorithmic software cost estimation model developed by Barry Boehm (1981). It estimates effort (person-months), development time (months) and staffing from the size of the software in thousands of delivered source lines (KLOC). It is a parametric estimating technique.

#### Models
1. **Basic COCOMO**: estimates from size only.
2. **Intermediate COCOMO**: adds 15 cost drivers (product, hardware, personnel, project attributes) as an effort adjustment factor (EAF).
3. **Detailed COCOMO**: applies drivers by phase.

#### Project modes (Basic COCOMO)
| Mode | Description | a | b | c | d |
|---|---|---|---|---|---|
| Organic | Small team, familiar problem, simple | 2.4 | 1.05 | 2.5 | 0.38 |
| Semi-detached | Medium team, mixed experience | 3.0 | 1.12 | 2.5 | 0.35 |
| Embedded | Tight constraints, hardware-dependent | 3.6 | 1.20 | 2.5 | 0.32 |

#### Formulas
- Effort E = a × (KLOC)ᵇ person-months
- Development time D = c × Eᵈ months
- Average staff = E / D persons

(Intermediate: E = a × (KLOC)ᵇ × EAF, with a = 3.2, 3.0, 2.8 for the three modes.)

#### Worked example: 50 KLOC product
| Mode | Effort (PM) | Time (months) | Staff |
|---|---|---|---|
| Organic | 2.4 × 50^1.05 = 145.9 | 2.5 × 145.9^0.38 = 16.6 | 8.8 |
| Semi-detached | 3.0 × 50^1.12 = 239.9 | 2.5 × 239.9^0.35 = 17.0 | 14.1 |
| Embedded | 3.6 × 50^1.20 = 393.6 | 2.5 × 393.6^0.32 = 16.9 | 23.3 |

**Answer (organic): effort about 146 person-months, time about 16.6 months, about 9 people.**

#### Advantages
- Simple, transparent, well documented, quick early estimate.

#### Limitations
- Depends on accurate size (KLOC) estimate.
- Calibrated on old data (1970s projects); not ideal for modern agile, reuse or RAD.
- Ignores some factors in the basic form.

COCOMO II (1995 onward) updates the model with Application Composition, Early Design and Post-Architecture stages, uses function points or object points, and scale factors.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What input does Basic COCOMO use to estimate effort, time and staffing?
   A. Number of team members
   B. Software size in KLOC
   C. Project budget in dollars
   D. Number of test cases
   Answer: B. COCOMO is parametric and estimates effort from software size in thousands of delivered source lines (KLOC). (Key point: What COCOMO estimates)

2. Which pair of formulas is Basic COCOMO?
   A. E = a x (KLOC)^b person-months; D = c x E^d months
   B. E = a x D^b; D = c x KLOC
   C. E = KLOC / D; D = a x E
   D. E = a + b x KLOC; D = c + d x E
   Answer: A. Effort E = a(KLOC)^b and development time D = c E^d; average staff = E/D. (Key point: Effort and time formulas)

3. Which mode has the highest effort coefficients (a = 3.6, b = 1.20) and suits tight, hardware-dependent projects?
   A. Organic
   B. Semi-detached
   C. Embedded
   D. Intermediate
   Answer: C. Embedded mode, with tight constraints, uses a = 3.6 and b = 1.20. (Key point: Project modes)

4. What does Intermediate COCOMO add to Basic COCOMO?
   A. Function points
   B. 15 cost drivers forming an effort adjustment factor (EAF)
   C. Three development phases only
   D. Scale factors and object points
   Answer: B. Intermediate COCOMO multiplies effort by an EAF based on 15 cost drivers. (Key point: Intermediate COCOMO)

5. For a 50 KLOC organic project, what is the approximate result?
   A. About 146 person-months, 16.6 months, about 9 people
   B. About 240 person-months, 17 months, about 14 people
   C. About 394 person-months, 17 months, about 23 people
   D. About 50 person-months, 5 months, 10 people
   Answer: A. E = 2.4 x 50^1.05 is about 145.9 PM, D about 16.6 months, staff = E/D about 8.8, so about 9. (Key point: Worked example result)