Software Quality Metrics : Introduction
Software quality metrics means the ability of a software product to be
and to perform as per the standard defined. Metric means standards.
The software quality metrics ensures that the software product is of
highest quality and standard.
There are three major software quality metrics. These are:
Software Quality Metrics
Software Quality Metrics : Customer Problem Metrics
The quality metrics used in software industry that is responsible for
measuring the problems encountered by the customers while using
the product.
From the customers point of view, all the problems they encountered
while using the software product are problems with the software
including the valid defects.
The usability problems, unclear documentation and errors are the
problems that cannot be considered as valid defects.
The customer problem metrics is usually expressed in terms of
problems per unit month i.e. PUM.
PUM =Total problems reported by a customer for a period of time + Total
number of license months of the software during the period.
Here,
No of license months = Number of install licenses of software * Number of
months in calculation period.
PUM is usually calculated for each month after the software is
released to the market, and also for monthly averages by year.
Software Quality Metrics : Customer Satisfaction Metrics
Customer Satisfaction Metric deals with the overall quality of the
product and how much a customer is satisfied with that software
product.
Customer satisfaction is often measured by customers survey data via
a five point scale. These are:
1. Very Satisfied.
2. Satisfied.
3. Neutral.
4. Dissatisfied.
5. Very Dissatisfied.
Customer Satisfaction Metrics
Based on a five point scale data, several metrics with slight variations
can be constructed and used. These are:
1. Percentages of completely satisfied customers.
2. Percentage of satisfied customers.
3. Percentage of dissatisfied customers.
4. Percentage of non-satisfied customers.
Note: Generally, ”Percentage of satisfied customers is used.”
Net Satisfaction Index(NSI) is also used by some companies for
customer satisfaction metrics.
The net satisfaction index ha following weighing criteria:
1. Completely Satisfied = 100%.
2. Satisfied = 75%.
3. Neutral = 50%.
4. Dissatisfied = 25%.
5. Completely Dissatisfied = 0%.
Software Quality Metrics : Software Maintenance Metrics
A software product can be called as in maintenance phase when its
development is complete and is released to the market.
During this interval, the defect arrival by time interval and customer
problem is called as de facto metrics.
Also, the number of defect or problems arrived mainly depends upon
the development phase and not on the maintenance phase.
Therefore, certain metrics are required for software maintenance.
These are:
1. Backlog Management Index(BMI)
The metric that is used to manage the backlog of open
and unresolved problems. It can be defined as:
BMI = (Number of problems closed during the month
* 100)/(Number of problems arrived during the
month)
2. Fix Response Time(FRT)
While developing the software product, certain guidelines
regarding reporting of defect are made. It includes the
guideline for time limit of fixes that must available
against the reported defects.
The fix response time for more severe defects is low and
the fix response time for less severe defect is high.
The fix response time metric can be calculated as:
FRT = (Mean time of all problems from open to closed)
3. Fix Quality
Fix quality of software product is the number of defects
fixed.
Every software product contains defects. But, Fix Quality
ensures that the defects in software product are fixed on
time as per the quality standard.
Fix quality ensures that the fixes for the defects should
not turn out to be defective.
A fix can be called as defective if it does not fixes the
problems and generates new problems in that software
product.
