Define product quality metrics in software testing in w3school
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Software metrics can be classified into three categories −
Product metrics − Describes the characteristics of the product such as size, complexity, design features, performance, and quality level.
Process metrics − These characteristics can be used to improve the development and maintenance activities of the software.
Project metrics − This metrics describe the project characteristics and execution. Examples include the number of software developers, the staffing pattern over the life cycle of the software, cost, schedule, and productivity.
Some metrics belong to multiple categories. For example, the in-process quality metrics of a project are both process metrics and project metrics.
Software quality metrics are a subset of software metrics that focus on the quality aspects of the product, process, and project. These are more closely associated with process and product metrics than with project metrics.
Software quality metrics can be further divided into three categories −
Product quality metrics
In-process quality metrics
Maintenance quality metrics
Product Quality Metrics
This metrics include the following −
Mean Time to Failure
Defect Density
Customer Problems
Customer Satisfaction
Mean Time to Failure
It is the time between failures. This metric is mostly used with safety critical systems such as the airline traffic control systems, avionics, and weapons.
Defect Density
It measures the defects relative to the software size expressed as lines of code or function point, etc. i.e., it measures code quality per unit. This metric is used in many commercial software systems.
Customer Problems
It measures the problems that customers encounter when using the product. It contains the customer’s perspective towards the problem space of the software, which includes the non-defect oriented problems together with the defect problems.
The problems metric is usually expressed in terms of Problems per User-Month (PUM).
PUM = Total Problems that customers reported (true defect and non-defect oriented problems) for a time period + Total number of license months of the software during the period
Where,
Number of license-month of the software = Number of install license of the software × Number of months in the calculation period
PUM is usually calculated for each month after the software is released to the market, and also for monthly averages by year.
Customer Satisfaction
Customer satisfaction is often measured by customer survey data through the five-point scale −
Very satisfied
Satisfied
Neutral
Dissatisfied
Very dissatisfied
Satisfaction with the overall quality of the product and its specific dimensions is usually obtained through various methods of customer surveys. Based on the five-point-scale data, several metrics with slight variations can be constructed and used, depending on the purpose of analysis. For example −
Percent of completely satisfied customers
Percent of satisfied customers
Percent of dis-satisfied customers
Percent of non-satisfied customers
Usually, this percent satisfaction is used.
In-process Quality Metrics
In-process quality metrics deals with the tracking of defect arrival during formal machine testing for some organizations. This metric includes −
Defect density during machine testing
Defect arrival pattern during machine testing
Phase-based defect removal pattern
Defect removal effectiveness
Defect density during machine testing
Defect rate during formal machine testing (testing after code is integrated into the system library) is correlated with the defect rate in the field. Higher defect rates found during testing is an indicator that the software has experienced higher error injection during its development process, unless the higher testing defect rate is due to an extraordinary testing effort.
This simple metric of defects per KLOC or function point is a good indicator of quality, while the software is still being tested. It is especially useful to monitor subsequent releases of a product in the same development organization.
Product metrics − Describes the characteristics of the product such as size, complexity, design features, performance, and quality level.
Process metrics − These characteristics can be used to improve the development and maintenance activities of the software.
Project metrics − This metrics describe the project characteristics and execution. Examples include the number of software developers, the staffing pattern over the life cycle of the software, cost, schedule, and productivity.
Some metrics belong to multiple categories. For example, the in-process quality metrics of a project are both process metrics and project metrics.
Software quality metrics are a subset of software metrics that focus on the quality aspects of the product, process, and project. These are more closely associated with process and product metrics than with project metrics.
Software quality metrics can be further divided into three categories −
Product quality metrics
In-process quality metrics
Maintenance quality metrics
Product Quality Metrics
This metrics include the following −
Mean Time to Failure
Defect Density
Customer Problems
Customer Satisfaction
Mean Time to Failure
It is the time between failures. This metric is mostly used with safety critical systems such as the airline traffic control systems, avionics, and weapons.
Defect Density
It measures the defects relative to the software size expressed as lines of code or function point, etc. i.e., it measures code quality per unit. This metric is used in many commercial software systems.
Customer Problems
It measures the problems that customers encounter when using the product. It contains the customer’s perspective towards the problem space of the software, which includes the non-defect oriented problems together with the defect problems.
The problems metric is usually expressed in terms of Problems per User-Month (PUM).
PUM = Total Problems that customers reported (true defect and non-defect oriented problems) for a time period + Total number of license months of the software during the period
Where,
Number of license-month of the software = Number of install license of the software × Number of months in the calculation period
PUM is usually calculated for each month after the software is released to the market, and also for monthly averages by year.
Customer Satisfaction
Customer satisfaction is often measured by customer survey data through the five-point scale −
Very satisfied
Satisfied
Neutral
Dissatisfied
Very dissatisfied
Satisfaction with the overall quality of the product and its specific dimensions is usually obtained through various methods of customer surveys. Based on the five-point-scale data, several metrics with slight variations can be constructed and used, depending on the purpose of analysis. For example −
Percent of completely satisfied customers
Percent of satisfied customers
Percent of dis-satisfied customers
Percent of non-satisfied customers
Usually, this percent satisfaction is used.
In-process Quality Metrics
In-process quality metrics deals with the tracking of defect arrival during formal machine testing for some organizations. This metric includes −
Defect density during machine testing
Defect arrival pattern during machine testing
Phase-based defect removal pattern
Defect removal effectiveness
Defect density during machine testing
Defect rate during formal machine testing (testing after code is integrated into the system library) is correlated with the defect rate in the field. Higher defect rates found during testing is an indicator that the software has experienced higher error injection during its development process, unless the higher testing defect rate is due to an extraordinary testing effort.
This simple metric of defects per KLOC or function point is a good indicator of quality, while the software is still being tested. It is especially useful to monitor subsequent releases of a product in the same development organization.
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