An Example of LOC Based Estimation

As an example of LOC and FP estimation methodology let us consider a software package to be established for a (CAD) computer-aided design application for mechanical parts.   A review of the system specification indicates which software is to execute on an engineering workstation and must interface with several computer graphics peripherals including a digitizer, mouse, high-resolution color display, and laser printer.

By using a system specification as a guide a preliminary statement of software scope can be established:

The CAD software will accept 2 and 3 dimensional geometric data from an engineer. Engineer will interact and control the CAD system by a user interface which will exhibit characteristics of good human machine interface design. The all geometric data and other supporting information will be maintained in a CAD database Design analysis modules will be established to produce needed output which will be displayed on a variety of graphics devices. Software will be designed to control and interact with peripheral devices which include a digitizer, mouse, and laser printer.

Above statement of scope is preliminary it is not restricted. Every sentence would have to be expanded to give quantitative bounding and concrete detail for example before estimation can start the planner must determine what characteristics of good human-machine interface design means and what the size or sophistication of the CAD database is to be.

For our purposes we suppose that the further refinement has occurred and that the following major software functions are identified:

• User interface and control facilities (UICF)

• Two-dimensional geometric analysis (2DGA)

• Three-dimensional geometric analysis (3DGA)

• Database management (DBM)

• Computer graphics display facilities (CGDF)
• Peripheral control (PC)

• Design analysis modules (DAM)

Figure - Estimation table of LOC method

There are the following three-point estimation methods for LOC the table shown in Figure 5.1 which is developed For example the range of LOC estimates for the 3D geometric analysis function is:

By applying equation (5.1) the expected value for the 3D geometric analysis function is   6800 LOC.  The number is entered in the table other estimates are derived in a same fashion. And by summing vertically in the estimated LOC column an estimate of 33,200 lines of code is build for the CAD system.

A review of historical data indicates which the organizational average productivity for systems of this kind is 620 LOC or pm which is Based on a burdened labor rate of $8000   per month the cost per line of code is approximately $13.00 Based on the LOC estimate and the historical productivity data the total estimated project cost is $431,000 and the estimated effort is 54 person-months.