Lawrence H. Putnam Case Study

Many estimating and planning tools are available but they all require that we first make a development estimate. These tools can be helpful in checking estimates and in managing planning mechanics.
 Putnam Model
This model is made by Lawrence H.putnam, which is based on Norden’s frequency distribution (Rayleigh curve).
Putnam model maps time and efforts required with software size.

 Cocomo model
Cocomo stands for Constructive cost model, developed by Barry W. Boehm. It divides the software product into three categories of software: organic, semidetached and embedded.

7. Algorithmic cost modelling
Algorithmic cost models are valuable to management as they support quantitative option analysis. They allow the cost of various options to be

Size may be either an assessment of the code size of the software or a functionality estimate expressed in function or object points. The value of exponent B usually lies between 1 and 1.5. It reflects the disproportionate effort required for large projects. M is a multiplier made up by combining different process, product and development attributes. All algorithmic models suffer from the same basic difficulties:
 It is often difficult to estimate Size at an early stage in a project where only a specification is available. Function point and object point estimates are easier to produce than estimates of code size but may still be inaccurate. 2. The estimates of the factors contributing to B and M are subjective. Estimates vary from one person to another depending on their background and

It also includes a means of estimating development schedules. The specific model which I mention early in this report. The Cocomo model is an empirical model. It was derived by collecting data from a large number of software projects, then analyzing that data to discover formulae that were the best-fit to the observations.
I have chosen Cocomo for the following reasons:

 It is well documented, in the public domain and is supported by public domain and commercial tools.
 It has been widely used and evaluated.

The first version of the Cocomo model (now known as COCOMBO 81) was a three-level model the levels reflected the detail of the analysis of the cost estimate. The first level (basic) provided an initial, rough estimate, the second level modified this using a number of project and process multipliers and the most detailed level produced estimates for different phases of the project. Cocomo 81 assumed that the software would be developed according to a waterfall process and that the vast majority of the software would be developed from scratch. However, there have been radical changes to software development since this initial version was proposed.
The basic COCOMBO 81