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Frequently Asked Questions (FAQs)

What does r2ESTIMATOR™ estimate?
r2ESTIMATOR™ estimates cost, schedule, effort, staffing, reliability (defects), and risk (probability of success).

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What is the basis of the math behind r2ESTIMATOR™?
r2ESTIMATOR™ implements the r2 Software Estimating Framework (r2SEF); a collection of generalized equations developed by Mike Ross that builds on original work done by Barry Boehm (COCOMO), Randy Jensen (Seer), and Larry Putnam, Sr. (SLIM) in the late 1970s and early 1980s. Their early work was based on data and assumptions that are now at least 25 years old. In the meantime, data from many thousands of projects have since been collected and offer an opportunity to revisit these old assumptions and relationships. The r2SEF set of equations contain several variables (exponents and multipliers) that provide the flexibility necessary to model the increasingly wide diversity of projects suggested by all this new project data.

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What are r2SEF categories and profiles?
The flexibility of the r2 Software Estimating Framework (r2SEF) lies in its notion of categories and profiles. An r2SEF category is a specific setting of certain r2SEF equation variables, the values of which are computed from a collection of related projects' historical data. In other words, an r2SEF category represents a unique software estimating model. An r2SEF profile is a specific setting of certain r2SEF equation variables that characterizes a particular project within some category.

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Can r2ESTIMATOR™ emulate the behavior of existing models such as COCOMO?
Yes. The flexibility provided by the r2SEF categories and profiles allows for the inclusion of other models in the framework. r2ESTIMATOR™ currently includes categories, profiles, and parameter input dialog boxes that specifically support COCOMO 81, COCOMO II, the Jensen Model (Seer), and the Norden-Putnam-Rayleigh (NPR) Model.

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Where do you get the data to create r2SEF categories and profiles?
r2Estimating, LLC continuously searches for and attempts to obtain historical project data from various sources. These sources include data for sale such as that from the International Software Benchmarking Standards Group (ISBSG); public domain data such as that collected by various agencies within the US government; data contained in published books, papers, and articles; data implied by public domain models; and data collected during consulting engagements. All of this data has been used to create a basic set of r2SEF categories and profiles, which we include in each r2Estimator release; however, users can create their own categories and profiles based on their own collected data, a practice we strongly encourage.

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Can we calibrate r2ESTIMATOR™ with our own data and how is that done?
Yes. If you have completed project data that includes size (content), effort (labor), duration (time), and post-delivery defects (optional), you can perform a fairly simple data regression process (or we can do this for you) to create and add a new r2SEF category to your installation of r2ESTIMATOR™.

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Does r2ESTIMATOR™ recognize different size metrics?
Yes. The nature of the r2SEF set of equations and the process used to create r2SEF categories and profiles is such that any reasonable size metric can be used to quantify the content of a particular software product. The basic set of categories included with r2ESTIMATOR™ assume size measured in either logical Source Lines of Code (SLOC) or International Function Points Users Group (IFPUG) Unadjusted Function Points (UFPs); however, when users create their own categories, they can choose to use any size metric that they deem appropriate for their particular type and style of development.

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How does r2ESTIMATOR™ handle risk?
r2ESTIMATOR™ expresses the risk associated with a key management metric output value (duration, effort, cost, and defects) in terms of its confidence probability (probability of meeting or exceeding the value). For example, I estimate this project will take two years to complete and I am 70% confident in this estimate; in other words, there is a 70% chance that the project will complete in two years or less. In order to provide this level of risk information, for each Work Breakdown Structure (WBS) element key management metric, r2ESTIMATOR™ inputs an uncertainty range (distribution of possible outcomes) provided by the user in the form of a [Lowest, Most Likely, Highest] triple. r2ESTIMATOR™ performs all of its estimation calculations with these uncertainty ranges using probability distribution (random variable) mathematics assisted by Monte Carlo simulation techniques. The results are key management metric outputs expressed in the form of probability distributions that show the range of possible outcomes and the probability of success associated with each possible outcome.

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What is a Ross chart?
A Ross chart (invented by Mike Ross) is a graphical display of the confidence (probability of success) and goal satisfaction of two correlated random variables. Key features include:

1. A two-dimensional Cartesian axis and coordinate system.

2. A line or curve representing the correlation between the two random variables.

3. Regions representing the function’s limits (reasonable range).

4. An interactive dynamic solution symbol (blue circle) on the curve representing a specific instance (solution) of the function.

5. Dynamic projection lines from the solution symbol to each axis.

6. Dynamic cumulative distribution range symbol on the axis-ends of each projection line (indexed in increments of 10% confidence probability), each range symbol representing its corresponding random variable’s confidence probability distribution, its color determined by whether (green) or not (red) the goal is satisfied within the confidence limit.

7. Interactive dynamic confidence limit (risk tolerance) symbol (blue triangle) on each cumulative distribution range symbol

8. Interactive dynamic goal symbol (blue diamond) on each axis representing the goal value associated with the corresponding variable.

In the above description interactive means the element can be moved (dragged). Interactive elements, by convention, are blue. Dynamic means the element moves in real time as the result of some other real time element movement.

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Can r2ESTIMATOR™ model activities other than software construction?
Yes. r2ESTIMATOR™ includes a rich set of Work Breakdown Structure (WBS) element types in addition to software Construction that include Decomposition, Integration, User-Defined, Cost Only, Milestone, Summary, and Project Summary. These key metrics of these elements can be specified as fixed amounts or as percentages of associated elements. This set of element types allows you to model things that may not be included in a basic software estimate like systems engineering, multiple levels of requirements specification, multiple levels of integration, program management, hardware and infrastructure development / purchase, testing environment hardware and software development / purchase, installation and deployment, user training, operations and maintenance support after delivery, etc.

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Does r2ESTIMATOR™ have online help?
Yes. The F1 key launches r2ESTIMATOR™ online help. Additionally, all r2ESTIMATOR™ dialog boxes contain a Help button that launches online help specifically related to that particular dialog box. This context-specific help includes parameter help for COCOMO 81, COCOMO II, the Jensen Model (Seer), and the Norden-Putnam-Rayleigh (NPR) Model.

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What export capabilities does r2ESTIMATOR™ have?
r2ESTIMATOR™ provides three distinct types of export: chart and report image export via the Microsoft Windows clipboard, customizable data export report to an XML file, and export to Microsoft Project.

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When exporting to Microsoft Project, what gets exported?
r2ESTIMATOR™'s export to Microsoft Project includes the entire project element hierarchy with schedule, effort, and cost information associated with each element. All of this is written to an XML-formatted file that can be opened by Microsoft Project.

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Can r2ESTIMATOR™ be integrated with other tools?
Yes. r2Estimator's project files and default files are formatted in XML which gives users open access to any r2ESTIMATOR™ project's inputs and outputs.

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What are the minimum computer requirements for running r2ESTIMATOR™?
To install and run r2ESTIMATOR™, you will need:

• Microsoft Windows 2000, NT 4.0 or later, XP, or Vista
• At least 128 MB RAM
• A monitor capable of displaying at least 800 x 600 pixels (1024 x 768 is recommended for the best display) with 256 colors and 96 dpi fonts (default small fonts). Large fonts will work provided the monitor is set to display more than 800 x 600 pixels.
• CD-ROM drive for installation

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