8/8/2019 Cost ion
1/22
Shashwat [email protected]
8/8/2019 Cost ion
2/22
8/8/2019 Cost ion
3/22
Estimating the cost of a Software product is one of the most difficult and error prone tasks.
Cost estimates can be of two types:1) Top down approach
2) Bottom up approach
8/8/2019 Cost ion
4/22
TOP DOWN APPROACH I t focuses on system level cost like computing resources as well as the cost of configuration
management ,quality assurance ,system integration ,training and publications.
I t focuses on system level cost but may overlook
various technical factors.
8/8/2019 Cost ion
5/22
BOTTOM UP APPROACH
I t first estimates the cost to develop each module and these cost are combined to arrive at an overall
estimate.
I t emphasizes the cost associated with developing individual system components but fail to account
for system level costs.
8/8/2019 Cost ion
6/22
METHODS FOR ESTIMATION
1) Expert Judgment 2) Delphi Cost Estimation
3) Work Breakdown Structures
4) Algorithmic Cost Models
8/8/2019 Cost ion
7/22
8/8/2019 Cost ion
8/22
Compute the estimate cost of the software system as the sum of costs of the modules and the
subsystem that comprises the system.They follow Bottom Up Approach.
8/8/2019 Cost ion
9/22
CONSTRUCTIVE COST MODEL
8/8/2019 Cost ion
10/22
8/8/2019 Cost ion
11/22
The following activities are covered by the estimates:
a) Covers estimate through acceptance testing
b) I ncludes the cost of documentation and reviews.
c) I ncludes the cost of Project Manager.
8/8/2019 Cost ion
12/22
The cost estimators exclude planning and analysis costs ,installation and training cost and
cost of computer operators , secretaries.The DS I (Delivered Source I nstruction) estimate
includes job control statement and source statements but excludes comments
I t is considered to be one line or card image.
8/8/2019 Cost ion
13/22
Following are the assumptions estimated by the
COCOMO concerning the nature of the software:-
1) Careful definition and validation of requirements is performed by a small number of capable people.2) Requirements remain stable throughout the
project 3) Careful definition and validation of architectural
designs is performed by a small number of capable people.
8/8/2019 Cost ion
14/22
4) Detailed design ,coding and unit testing are performed in parallel by group of programmers
working in teams.5) I ntegration Testing is based on early test
planning.
6) I nterface errors are found by unit testing and by inspections.
8/8/2019 Cost ion
15/22
F ormally there are mainly 10 steps to estimate the cost using COCOMO:-
1) I dentify all the subsystem and modules in the product.
2) Estimate the size of each module and calculate the size of each subsystem and the total system.
8/8/2019 Cost ion
16/22
3) Specify the module level multipliers.4) Compute the module effort and the time
estimates for each modules.5) Specify the effort multipliers for each
subsystems.6) F rom Steps 4 and 5 compute the estimated
effort and development time for each subsystems.
8/8/2019 Cost ion
17/22
7 ) F rom Step 6 compute the total system effort and development time.
8) Perform sensitivity analysis on the estimate.9) Add other development cost like planning and analysis that are not included in the estimates.
10) Compare this estimate with the one developed by Delphi estimation .I dentify and Rectify the differences in the estimates.
8/8/2019 Cost ion
18/22
MODULE LEVEL MULTIPLIERS Product Complexity
Programmers Capability Virtual Machine Experience
Programming Language Experience
8/8/2019 Cost ion
19/22
8/8/2019 Cost ion
20/22
PRODUCT ATTR I BUTES
Required Reliability Data-base Size Product Complexity
COMPUTER ATTR I BUTES
Execution time constraint Main storage Constraint Virtual machine reality
Computer turnaround time
8/8/2019 Cost ion
21/22
ADVANTAGES:-o The model can be used to gain insight into the cost
factors.o Systematic techniques of software engineering are
used throughout the development process.o Data can be collected and analyzed ,new factors
can be identified and effort multipliers can be adjusted.
8/8/2019 Cost ion
22/22
Shashwat [email protected]
Top Related