Individuals assess components, then component estimates are summed to obtain total estimate. Perform overall estimate using design parameters and mathematical algorithms. Advantages Estimates are based on actual experience. More applicable to early project estimates. Considers system level activities, faster, easier to implement.
Models are usually fast and easy to use, and useful early in a program.
They are also objective and repeatable. Limitations Truly similar projects must exist. Methods are time- consuming. Detailed data needed may not be available, especially early in a program. Integration costs may be disregarded.