PRICE-S

This model was developed originally by Martin Marietta Price Systems (initially RCA Price, then GE Price) as one of a family of models for hardware and software cost estimation. Developed in 1977 by F. Freiman and Dr. R. Park, it was the first commercially available detailed parametric software cost model to be extensively marketed and used. In 1987, the model was modified and re-validated for modern software development practices. The PRICE-S model is proprietary, it can be leased for yearly use on IBM or compatible PC, and operates within Microsoft windows. It is also available for use on a UNIX workstation. The model is applicable to all types of software projects, and considers all DOD-STD-2167A development phases.

Inputs

One of the primary inputs for the PRICE-S model is source lines of code (SLOC). This may be input by the user or computed using either object-oriented or function point sizing models. Both sizing models are included in the PRICE-S package. Other key inputs include:

1. Application: a measure of the type (or types) of software, described by one of seven categories (mathematical, string manipulation, data storage and retrieval, on-line, real-time, interactive, or operating system).
2. Productivity Factor: A calibrated parameter which relates the software program to the productivity, efficiency/inefficiencies, software development practices and management practices of the development organization.
3. Complexities: Three complexity parameters which relate the project to the expected completion time, based on organizational experience, personnel, development tools, hardware characteristics, and other complicating factors.
4. Platform: the operating environment, in terms of specification, structure and reliability requirements.
5. Utilization: Percentage of hardware memory or processing speed utilized by the software.
6. New Design/New Code: Percentage of new design and new code.
7. Integration (Internal): Effort to integrate various software components together to form an integrated and tested CSCI.
8. Integration (External): Effort to integrate various software CSCI's together to form an integrated and tested software system.
9. Schedule: Software project start and/or end dates.
10. Optional Input Parameters: Financial factors, escalation, risk simulation.

Processing

The PRICE-S algorithms are published in the paper entitled "Central Equations of PRICE S" which is available from PRICE Systems. It states that PRICE-S computes a "weight" of software based on the product of instructions and application inputs. The productivity factor and complexity inputs are very sensitive parameters which affect effort and schedule calculations. Platform is known to be an exponential input; hence, it can be very sensitive. A new weighted design and code value are calculated by the model based on the type or category of instructions. Both new design and code affect schedule and cost calculations. Internal integration input parameters affect the CSCI cost and schedule for integrating and testing the CSCI. The external integration input parameter is used to calculate software to software integration cost and schedule.

Outputs

PRICE-S computes an estimate in person effort (person hours or months). Effort can be converted to cost in dollars or other currency units using financial factors parameters. Software development schedules are calculated for nine DOD-STD-2167A phases: System Concept through Operational Test and Evaluation. Six elements of costs are calculated and reported for each schedule phase: Design Engineering, Programming, Data, Systems Engineering Project Management, Quality Assurance, and Configuration Management. The PRICE-S model also contains several optional outputs including over thirty graphs, Gantt charts, sensitivity matrices, resource expenditure profiles, schedule reports. In addition, Microsoft Project files, spreadsheet files, and risk analysis reports can be generated. The risk analysis report is a Cumulative Probability Distribution and is generated using either Monte Carlo or Latin Hypercube simulation.

Calibration

The PRICE-S model can be run in ECIRP (PRICE backwards) mode to calibrate selected parameters. The most common calibration is that of the productivity factor, which, according to the PRICE-S manual, tends to remain constant for a given organization. It is also possible to calibrate platform, application, and selected internal factors.

Life Cycle Considerations

The PRICE-S life cycle model, included in the PRICE-S package, is a detailed model which computes software support costs. The primary inputs include PRICE-S development inputs, support descriptors which include software support life, number of installations, expected growth, and support productivity factors. The model also has a modification mode which allows up to four modifications per software CSCI. The PRICE-S life cycle model calculates support effort and outputs the cost in three support phases: maintenance, enhancements, and growth. The model allocates effort or cost across six elements of costs for each support phase.

Risk Analysis

The PRICE-S model contains a robust Monte Carlo simulation utility, which facilitates rigorous risk analysis. Uncertainty can be characterized using probability distributions to define input parameters. Normal, Beta, Triangular and Uniform distributions are among those available. Simulation results are consolidated and reported as a probabilistic estimate.

Contact

Lockheed-Martin PRICE Systems

700 East Gate Drive, Suite 200

Mt. Laurel, NJ 08054

(800) 437-7423 a.k.a. (800) 43PRICE