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- 1. The Requirement
- 2. Rationale
- 3. Guidance
- 4. Small Projects
- 5. Resources
- 6. Lessons Learned
- 7. Software Assurance
1. Requirements
5.3.4 The project manager shall, for each planned software peer review or software inspection, record necessary measurements.
1.1 Notes
NPR 7150.2, NASA Software Engineering Requirements, does not include any notes for this requirement.
1.2 History
1.3 Applicability Across Classes
Class A B C D E F Applicable?
Key: - Applicable | - Not Applicable
2. Rationale
As with other engineering practices, it is important to monitor defects, pass/fail results, and effort. This is necessary to ensure that peer reviews and software inspections are being used appropriately as part of the overall software development life cycle, and to be able to improve the process itself over time. Moreover, key measurements are required to interpret inspection results correctly. For example, if very little effort is expended on an inspection or key phrases (such as individual preparation) are skipped altogether, it is very unlikely that the inspection will have found a majority of the existing defects.
3. Guidance
3.1 Best Practices
NASA-STD-8739.9, Software Formal Inspections Standard, includes lessons that have been learned by practitioners over the last decade.
The Software Formal Inspections Standard suggests several best practices related to the collection and the use of inspection data. 277
This requirement collects effort, the number of participants, defects, number and types of defects found pass/fail, and identification to ensure the effectiveness of the inspection. Where peer reviews and software inspections yield less than expected results, some questions to address may include:
- Are peer reviews/inspections being deployed for the appropriate artifacts? As described in the rationale for SWE-087 - Software Peer Reviews and Inspections for Requirements, Plans, Design, Code, and Test Procedures, this process often is most beneficial when applied to artifacts such as requirements and test plans. See also Topic 7.10 - Peer Review and Inspections Including Checklists
- How are peer reviews and software inspections being applied concerning other verification and validation (V&V) activities? It may be worth considering whether this process is being applied only after other approaches to quality assurance (e.g., unit testing) that are already finding defects, perhaps less cost-effectively.
- Are peer review and software inspection practices being followed appropriately? Tailoring away key parts of the inspection process (e.g., planning or preparation), or undertaking inspections with key expertise missing from the team, will not produce the best results.
See also 5.03 - Inspect - Software Inspection, Peer Reviews, Inspections
3.2 Collection and Analysis of Data
As with other forms of software measurement, best practices for ensuring that the collection and analysis of peer review and software inspection metrics are done well include:
- Clear triggers indicate when the metrics are gathered and analyzed (e.g., after every inspection; once per month).
- Clear task assignments for this task.
- Consistent recording of the units of measure, (e.g., one inspection does not record effort in person-hours and another in calendar days).
- Consistency checking for collected measures, including investigation of outliers to verify whether the data was entered correctly and the correct definitions were applied.
Best practices related to the collection and analysis of inspection data include:
- The moderator is responsible for compiling and reporting the inspection data.
- The project manager explicitly specifies the location and the format of the recorded data.
- Inspections are checked for process compliance using the collected inspection data, for example, to verify that:
- Any inspection team consists of at least three persons.
- Any inspection meeting is limited to approximately 2 hours, and if the discussion looks likely to extend far longer, the remainder of the meeting is rescheduled for another time when inspectors can be fresh and re-focused.
- The rate of inspection adheres to the recommended or specified rate for different inspection types.
- A set of analyses is performed periodically on the recorded data to monitor progress (i.e., number of inspections planned versus completed) and to understand the costs and benefits of inspection.
- The outcome of the analyses is leveraged to support the continuous improvement of the inspection process.
3.3 Metrics for Projects Using Acquisition
In an acquisition context, there are several important considerations for assuring proper inspection usage by software provider(s):
- The metrics to be furnished by the software provider(s) must be specified in the contract.
- It must be clear and agreed upon ahead of time whether or not software providers can define their defect taxonomies. If providers may use their taxonomy, request that the software providers furnish the definition or the data dictionary of the taxonomy. It is also important (especially when the provider team contains subcontractors) to ensure that consistent definitions are used for: defect types; defect severity levels; effort reporting (how comprehensive or restrictive are the activities that are part of the actual inspection).
3.4 Base Metrics
Examples of Software Peer Review Base Metrics
Category | Base Metric | Description |
Size | Size planned | Lines of code or document pages that you planned to inspect |
Size | Size Actual | Lines of code or documents pages that were inspected or peer-reviewed |
Time | Time Meeting | The time required to complete the inspection, if done over several meetings then add up the total time required |
Effort | Planning | Total number of hours spent planning and preparing for the review |
Meeting time | Total number of hours spent in the inspection meeting (multiply the Time meeting by the number of participates | |
Rework | The total number of hours spent by the author making improvements based on the findings. | |
Defects | Major Defects found | Number of Major defects found during the review |
Minor Defect found | Number of Minor defects found during the review | |
Major Defects Corrected | Number of major defects corrected during rework | |
Minor Defects Corrected | Number of minor defects corrected during rework | |
Other | Number of Inspectors | Number of people, not counting observers, who participated in the review |
Product Appraisal | Review teams assessment of the work product (accepted, accepted conditionally, review again following rework, review not complete, etc.) | |
Derived Data | Peer Review Defects | The Peer Review Defect metric measures the average number of defects per peer review to determine defect density over time. Number of defects found per Peer Review = [Total number of defects] / [To number of Peer Reviews] |
3.5 Additional Guidance
Additional guidance related to this requirement may be found in the following materials in this Handbook:
Related Links |
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3.6 Center Process Asset Libraries
SPAN - Software Processes Across NASA
SPAN contains links to Center managed Process Asset Libraries. Consult these Process Asset Libraries (PALs) for Center-specific guidance including processes, forms, checklists, training, and templates related to Software Development. See SPAN in the Software Engineering Community of NEN. Available to NASA only. https://nen.nasa.gov/web/software/wiki 197
See the following link(s) in SPAN for process assets from contributing Centers (NASA Only).
SPAN Links |
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4. Small Projects
Projects with small budgets or a limited number of personnel need not use complex or user-intensive data collection logistics.
Given the amount of data typically collected, well-known and easy-to-use tools such as Excel sheets or small databases (e.g., implemented in MS Access) are usually sufficient to store and analyze the inspections performed on a project.
5. Resources
5.1 References
- (SWEREF-197) Software Processes Across NASA (SPAN) web site in NEN SPAN is a compendium of Processes, Procedures, Job Aids, Examples and other recommended best practices.
- (SWEREF-235) John C. Kelly, Joseph S. Sherif, Jonathan Hops, NASA. Goddard Space Flight Center, Proceedings of the 15th Annual Software Engineering Workshop; 35 p
- (SWEREF-277) NASA-STD-8739.9, NASA Office of Safety and Mission Assurance, 2013. Change Date: 2016-10-07, Change Number: 1
5.2 Tools
NASA users find this in the Tools Library in the Software Processes Across NASA (SPAN) site of the Software Engineering Community in NEN.
The list is informational only and does not represent an “approved tool list”, nor does it represent an endorsement of any particular tool. The purpose is to provide examples of tools being used across the Agency and to help projects and centers decide what tools to consider.
6. Lessons Learned
6.1 NASA Lessons Learned
No Lessons Learned have currently been identified for this requirement.
6.2 Other Lessons Learned
- Throughout hundreds of inspections and analyses of their results, the Jet Propulsion Laboratory (JPL) has identified key lessons learned that lead to more effective inspections 235, including:
- Capturing statistics on the number of defects, the types of defects, and the time expended by engineers on the inspections.
7. Software Assurance
7.1 Tasking for Software Assurance
7.2 Software Assurance Products
- None at this time.
Objective Evidence
- Peer review metrics, reports, data, or findings
- List of participants in the software peer reviews
- Defect or problem reporting tracking data
- Software assurance audit reports on the peer-review process
7.3 Metrics
- # of Non-Conformances from reviews (Open vs. Closed; # of days Open)
- Preparation time each review participant spent preparing for the review
- Time required to close peer review audit Non-Conformances
- Trends on non-conformances from audits (Open, Closed, Life cycle Phase)
- # of peer review Non-Conformances per work product vs. # of peer reviewers
- # of peer review participants vs. total # invited
- Total # of peer review Non-Conformances (Open, Closed)
- # of Non-Conformances identified by software assurance during each peer review
- # of Non-Conformances identified in each peer review
- # of peer reviews performed vs. # of peer reviews planned
- Time required to close review Non-Conformances
- Preparation time each audit participant spent preparing for audit
See also Topic 8.18 - SA Suggested Metrics.
7.4 Guidance
Software Assurance needs to confirm that all the measurements from any peer reviews are collected and stored after the review. Centers may have a standard set of metrics to be collected for peer reviews contained in their process asset library. If so, software assurance should verify that the appropriate set was recorded. There is also a set of recommended metrics in the software guidance portion of this requirement. An additional useful piece of information to record is the type of product that is being inspected.
Software assurance may want to collect some measures on their involvement in the peer reviews with two objectives in mind:
- To improve the effort estimates concerning the amount of software assurance that is usually needed for various types of peer reviews. A sample set of assurance metrics to collect for each type of peer review are:
- The number of software assurance personnel that participated in the peer review
- The number of hours spent in assuring that peer review planning and close-out activities were performed as required by NPR-7150.2
- The number of hours the software assurance personnel spent reviewing the peer review material before the meeting
- The number of hours spent in the peer review meeting
- The number of hours software assurance spent tracking the peer review findings to closure
- To demonstrate the value of software assurance participation in peer reviews collect:
- The number of issues, and defects found by software assurance
- A list of the issues, defects found, and their severity
7.5 Additional Guidance
Additional guidance related to this requirement may be found in the following materials in this Handbook: