An empirical relationship
It is the technique to Recalling the software equation which was introduced in the past lecture. We can demonstrate the highly nonlinear relationship among chronological time to human effort and complete a project applied to the project. Number of delivered lines of code L is associated to development time and effort through the equation:
L = P X (E/B) 1/3 T 4/3
Where E is a development effort in person months P is a productivity parameter which reflects a variety of factors which lead to high quality software engineering work and t is the project duration in calendar months. B is a special skill factor which ranges among 0.16, 0.39 and is a function of the size of the software to be produced
Rearranging the software equation above, we have to arrive at an expression for development effort E.
D =L3/ (P3T4)
Where E is the effort expended over the entire life cycle for maintenance and software development and T is the development time period in years. The equation for development effort can be associated to development cost through the inclusion of a burdened labour rate factor ($/person-year).
This will leads to some interesting results. Now consider a complex real time software project estimated at 33,000 LOC 12 person years of efforts. If 8 people are assigned to the project team the project can be completed in approximately in year 1.3. If however we extend the end date to years 1.75 the highly nonlinear nature of the model define in the equation 7, .1 yields
E= L3/ (P3T4) ~3.8 person years.
This implies that through extending the end date 6 months we can reduce the number of people from 8 to 4! The validity of like those results is open to debate but the implication is clear the advantages can be gained through using fewer people over a somewhat longer time span to accomplish the similar goal.