· COCOMO (Constructive Cost Estimation Model) was proposed by Boehm
· According to Boehm, software cost estimation should be done through three stages:
o Basic COCOMO,
o Intermediate COCOMO, and
o Complete COCOMO
· The basic COCOMO model gives an approximate estimate of the project parameters
· The basic COCOMO estimation model is given by the following expressions
????????????=??1(????????)??2 ????
????????=??1(????????????)??2 ????????h??
o KLOC is the estimated size of the software product expressed in Kilo Lines of Code,
o a1, a2, b1, b2 are constants for each category of software products,
o Tdev is the estimated time to develop the software, expressed in months,
o Effort is the total effort required to develop the software product, expressed in person months (PMs).
· The effort estimation is expressed in units of person-months (PM)
· It is the area under the person-month plot
· Every line of source text should be calculated as one LOC irrespective of the actual number of instructions on that line
· If a single instruction spans several lines (say n lines), it is considered to be nLOC
· The values of a1, a2, b1, b2 for different categories of products (i.e. organic, semidetached, and embedded) as given by Boehm
He derived the expressions by examining historical data collected from a large number of actual projects
