Cocomo model software estimation

From fig, we can observe that the effort is somewhat superliner in the size of the software product. Thus, the effort required to develop a product increases very rapidly with project size. The development time versus the product size in KLOC is plotted in fig. From fig it can be observed that the development time is a sub linear function of the size of the product, i.

This can be explained by the fact that for larger products, a larger number of activities which can be carried out concurrently can be identified. The parallel activities can be carried out simultaneously by the engineers. This reduces the time to complete the project. Further, from fig, it can be observed that the development time is roughly the same for all three categories of products. For example, a 60 KLOC program can be developed in approximately 18 months, regardless of whether it is of organic, semidetached, or embedded type.

From the effort estimation, the project cost can be obtained by multiplying the required effort by the manpower cost per month. But, implicit in this project cost computation is the assumption that the entire project cost is incurred on account of the manpower cost alone.

In addition to manpower cost, a project would incur costs due to hardware and software required for the project and the company overheads for administration, office space, etc.

It is important to note that the effort and the duration estimations obtained using the COCOMO model are called a nominal effort estimate and nominal duration estimate. The term nominal implies that if anyone tries to complete the project in a time shorter than the estimated duration, then the cost will increase drastically.

But, if anyone completes the project over a longer period of time than the estimated, then there is almost no decrease in the estimated cost value. Calculate the effort and development time for each of the three model i. Software development team has average experience on similar type of projects.

The project schedule is not very tight. Calculate the Effort, development time, average staff size, and productivity of the project.

Solution: The semidetached mode is the most appropriate mode, keeping in view the size, schedule and experience of development time. Intermediate Model: The basic Cocomo model considers that the effort is only a function of the number of lines of code and some constants calculated according to the various software systems. The detailed model uses various effort multipliers for each cost driver property. In detailed cocomo, the whole software is differentiated into multiple modules, and then we apply COCOMO in various modules to estimate effort and then sum the effort.

The effort is determined as a function of program estimate, and a set of cost drivers are given according to every phase of the software lifecycle. Intermediate COCOMO computes software development effort as function of program size and a set of 'cost drivers' that include subjective assessment of product, hardware, personnel and project attributes. This extension considers a set of four 'cost drivers', each with a number of subsidiary attributes Each of the 15 attributes receives a rating on a six-point scale that ranges from 'very low' to 'extra high' in importance or value.

An effort multiplier from the table below applies to the rating. The product of all effort multipliers results in an effort adjustment factor EAF. Typical values for EAF range from 0. The coefficient a i and the exponent b i are given in the next table. Model effort multipliers, EMi, and 6 for the Early Design model. SFj stands for the exponential scale factors. It is a procedural cost estimate model for software projects and often used as a process of reliably predicting the various parameters associated with making a project such as size, effort, cost, time and quality.

It was proposed by Barry Boehm in and is based on the study of 63 projects, which make it one of the best-documented models. It is measured in person-months units. Schedule: Simply means the amount of time required for the completion of the job, which is, of course, proportional to the effort put. It is measured in the units of time such as weeks, months.

Different models of Cocomo have been proposed to predict the cost estimation at different levels, based on the amount of accuracy and correctness required. All of these models can be applied to a variety of projects, whose characteristics determine the value of constant to be used in subsequent calculations. These characteristics pertaining to different system types are mentioned below. Semi-detached — A software project is said to be a Semi-detached type if the vital characteristics such as team-size, experience, knowledge of the various programming environment lie in between that of organic and Embedded.

The projects classified as Semi-Detached are comparatively less familiar and difficult to develop compared to the organic ones and require more experience and better guidance and creativity. Embedded — A software project with requiring the highest level of complexity, creativity, and experience requirement fall under this category.

Such software requires a larger team size than the other two models and also the developers need to be sufficiently experienced and creative to develop such complex models. All the above system types utilize different values of the constants used in Effort Calculations. Any of the three forms can be adopted according to our requirements. Its accuracy is somewhat restricted due to the absence of sufficient factor considerations.