Metrics for product development

Taxonomy of Metrics:

Metrics for certain aspects of the project include:

• Progress in terms of size and complexity.
• Stability in terms of rate of change in the requirements or implementation, size, or complexity.
• Modularity in terms of the scope of change.
• Quality in terms of the number and type of errors.
• Maturity in terms of the frequency of errors.
• Resources in terms of project expenditure versus planned expenditure

Metric	Purpose	Sample measures/perspectives
Progress	Iteration planning Completeness	Number of classes SLOC Function points Scenarios Test cases These measures may also be collected by class and by package Amount of rework per iteration (number of classes)
Stability	Convergence	Number and type of changes (bug versus enhancement; interface versus implementation) This measure may also be collected by iteration and by package Amount of rework per iteration
Adaptability	Convergence Software "rework"	Average person-hours/change This measure may also be collected by iteration and by package
Modularity	Convergence Software "scrap"	Number of classes/categories modified per change This measure may also be collected by iteration
Quality	Iteration planning Rework indicator Release criterion	Number of errors Defect discovery rate Defect density Depth of inheritance Class coupling Size of interface (number of operations) Number of methods overridden Method size These measures may also be collected by class and by package
Maturity	Test coverage/adequacy Robustness for use	Test hours/failure and type of failure This measure may also be collected by iteration and by package
Expenditure profile	Financial insight Planned versus actual	Person-days/class Full-time staff per month % budget expended

A Complete Metrics Set

Ø  The Process:-  the sequence of activities invoked to produce the software product (and other artifacts)

Ø  The Product:- the artifacts of the process, including software, documents and models

Ø  The Project:- the totality of project resources, activities and artifacts

Ø  The Resources:- the people, methods and tools, time, effort and budget, available to the project

Process Metrics:
Short-term metrics that measure the effectiveness of the product development process and can be used to predict program and product performance
- Staffing (hours) vs. plan
- Turnover rate
- Errors per 1,000 lines of code (KSLOC)

Metrics	Comments
Duration	Elapsed time for the activity
Effort	Staff effort units (staff-hours, staff-days, ...)
Output	Artifacts and their size and quantity (note this will include defects as an output of test activities)
Software development environment usage	CPU, storage, software tools, equipment (workstations, PCs), disposables. Note that these may be collected for a project by the Software Engineering Environment Authority (SEEA).
Defects, discovery rate, correction rate.	Total repair time/effort and total scrap/rework (where this can be measured) also needs to be collected; will probably come from information collected against the defects (considered as artifacts).
Change requests, imposition rate, disposal rate.	Comments as above on time/effort.
Other incidents that may have a bearing on these metrics (freeform text)	This is a metric in that it is a record of an event that affected the process.
Staff numbers, profile (over time) and characteristics
Staff turnover	A useful metric which may explain at a post-mortem review why a process went particularly well, or badly.
Effort application	The way effort is spent during the performance of the planned activities (against which time is formally recorded for cost account management) may help explain variations in productivity: some subclasses of effort application are, for example: ·         Training ·         Familiarization ·         Management (by team lead, for example) ·         Administration ·         Research ·         Productive work—it's helpful to record this by artifact, and attempt a separation of 'think' time and capture time, particularly for documents. This will tell the project manager how much of an imposition the documentation process is on the engineer's time. ·         Lost time ·         Meetings ·         Inspections, walkthroughs, reviews - preparation and meeting effort (some of these will be separate activities and time and effort for them will be recorded against a specific review activity)
Inspections, walkthroughs, reviews (during an activity - not separately scheduled reviews)	Record the number of these and their duration, and the number of issues raised.
Process deviations (raised as non-compliances, requiring project change)	Record the numbers of these and their severity. This is an indicator that more education may be required, that the process is being misapplied, or that the way the process was configured was incorrect
Process problems (raised as process defects, requiring process change)	Record the number of these and their severity. This will be useful information at the post-mortem reviews and is essential feedback for the Software Engineering Process Authority (SEPA).

Product development Metrics
Artifacts:

·         Size — a measure of the number of things in a model, the length of something, the extent or mass of something

·         Quality

§  Defects — indications that an artifact does not perform as specified or is not compliant with its specification, or has other undesirable characteristics

§  Complexity — a measure of the intricacy of a structure or algorithm: the greater the complexity, the more difficult a structure is to understand and modify, and there is evidence that complex structures are more likely to fail

§  Coupling — a measure of how extensively elements of a system are interconnected

§  Cohesion — a measure of how well an element or component meets the requirement of having a single, well-defined, purpose

§  Primitiveness — the degree to which operations or methods of a class can be composed from others offered by the class

·         Completeness — a measure of the extent to which an artifact meets all requirements (stated and implied—the Project Manager should strive to make explicit as much as possible, to limit the risk of unfulfilled expectations). We have not chosen here to distinguish between sufficient and complete.

·         Traceability — an indication that the requirements at one level are being satisfied by artifacts at a lower level, and, looking the other way, that an artifact at any level has a reason to exist

·         Volatility — the degree of change in an artifact because of defects or changing requirements

·         Effort — a measure of the work (staff-time units) that is required to produce an artifact

Documents:

Characteristic	Metrics
Size	Page count
Effort	Staff-time units for production, change and repair
Volatility	Numbers of changes, defects, opened, closed; change pages
Quality	Measured directly through defect count
Completeness	Not measured directly: judgment made through review
Traceability	Not measured directly: judgment made through review

Models:

§  Use-Case Model

Characteristic	Metrics
Size	Number of Use Cases        Number of Use Case Packages        Reported Level of Use Case (see white paper, "The Estimation of Effort and Size based on Use Cases" from the Resource Center)        Number of scenarios, total and per use case        Number of actors        Length of Use Case (pages of event flow, for example)
Effort	Staff-time units (with production, change and repair separated)
Volatility	Number of defects and change requests (open, closed)
Quality	Reported complexity (0-5, by analogy with COCOMO [BOE81], at class level; complexity range is narrower at higher levels of abstraction - see white paper, "The Estimation of Effort and Size based on Use Cases" from the Resource Center)        Defects — number of defects, by severity, open, closed
Completeness	Use Cases completed (reviewed and under configuration management with no defects outstanding)/use cases identified (or estimated number of use cases)
Traceability	Analysis o    Scenarios realized in analysis model/total scenarios        Design o    Scenarios realized in design model/total scenarios        Implementation o    Scenarios realized in implementation model/total scenarios        Test o    Scenarios realized in test model (test cases)/total scenarios

§  Design Model

Characteristic	Metrics
Size	Number of classes        Number of design subsystems        Number of subsystems of subsystems .        Number of packages        Methods per class, internal, external        Attributes per class, internal, external        Depth of inheritance tree        Number of children
Effort	Staff-time units (with production, change and repair separated)
Volatility	Number of defects and change requests (open, closed)
Quality	Complexity	Response For a Class (RFC): this may be difficult to calculate because a complete set of interaction diagrams is needed.
	Coupling	Number of children        Coupling between objects (class fan-out)
	Cohesion	Number of children
	Defects	Number of defects, by severity (open, closed)
Completeness	Number of classes completed/number of classes estimated (identified)        Design traceability (in Use-Case model)
Traceability	Number of classes in Implementation Model/number of classes

§  Implementation Model

Characteristic	Metrics
Size	Number of classes        Number of components        Number of implementation subsystems        Number of subsystems of subsystems .        Number of packages        Methods per class, internal, external        Attributes per class, internal, external        Size of methods*        Size of attributes*        Depth of inheritance tree        Number of children        Estimated size* at completion
Effort	Staff-time units (with production, change and repair separated)
Volatility	Number of defects and change requests (open, closed)        Breakage* for each corrective or perfective change, estimated (prior to fix) and actual (upon closure)
Quality	Complexity	Response For a Class (RFC)        Cyclomatic complexity of methods**
	Coupling	Number of children        Coupling between objects (class fan-out)        Message passing coupling (MPC)***
	Cohesion	Number of children        Lack of cohesion in methods (LCOM)
	Defects	Number of defects, by severity, open, closed
Completeness	Number of classes unit tested/number of classes in design model        Number of classes integrated/number of classes in design model        Implementation traceability (in Use-Case model)        Test model traceability multiplied by Test Completeness        Active integration and system test time (accumulated from test process), that is, time with system operating (used for maturity calculation)

§  Test Model

Characteristic	Metrics
Size	Number of Test Cases, Test Procedures, Test Scripts
Effort	Staff-time units (with production, change and repair separated) for production of test cases, and so on
Volatility	Number of defects and change requests (open, closed)—against the test model
Quality	Defects — number of defects by severity, open, closed (these are defects raised against the test model itself, not defects raised by the test team against other software)
Completeness	Number of test cases written/number of test cases estimated        Test traceability (in Use-Case model)        Code coverage
Traceability	Number of Test Cases reported as successful in Test Evaluation Summary/Number of test cases

§  Management

Change Model—this is a notional model for consistent presentation—the metrics will be collected from whatever system is used to manage Change Requests.

Characteristic	Metrics
Size	Number of defects, change requests by severity and status, also categorized as number of perfective changes, number of adaptive changes and number of corrective changes.
Effort	Defect repair effort, change implementation effort in staff-time units
Volatility	Breakage (estimated, actual) for the implementation model subset.
Completeness	Number of defects discovered/number of defects predicted (if a reliability model is used)

Project Metrics

·         BCWS, Budgeted Cost for Work Scheduled

·         BCWP, Budgeted Cost for Work Performed

·         ACWP, Actual Cost of Work Performed

·         BAC, Budget at Completion

·         EAC, Estimate at Completion

·         CBB, Contract Budget Base

·         LRE, Latest Revised Estimate (EAC)

Resources Metrics:

·         People (experience, skills, cost, performance),

·         Methods and tools (in terms of effect on productivity and quality, cost),

·         Time, effort, budget (resources consumed, resources remaining)