Software Reliability

Software Quality Tutorial



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Software Reliability : Introduction

  • Software Reliability can be defined as the ability of a software product to perform consistently and be trustworthy to its users i.e. The software product must perform as required and should not deviate from its goal. 
  • Reliability means trustworthy or consistent.
  • Reliability of a software product is an important aspect as it shows the actual ability of the software product.

 

Software Reliability : Software Metrics

  • Software metrics are the standards of measurement for a software product for certain properties and functionalities. Software metrics can be broadly classified into three categories. These are listed below :

 

This image describes the software metrics used to check for software reliability in software quality.

Software Metrics : Software Reliability

 

  1. Process Metrics
  • The Process Metric are used for the improvement of the development and maintenance of a software product. It mainly measures the efficiency of the software product.
  1. Product Metrics
  • The Product Metric are used for demonstrating the software product characteristics and features such as the performance and its quality.
  1. Project Metrics
  • The Project Metrics are used for demonstrating the characteristics of whole software project which includes the total time, total cost, productivity and teams.

 

Software Reliability : Defect Rate

  • Defect Rate can be defined as the number of defect detected per unit the number of test cycles.

Defect Rate = (No of Defects Detected* 100)/ (No of Test Cycles)

 

Software Reliability : Defect Density

  • Defect density is defined as the number of defects arrived during a specific period of time per unit the size of software/module.

Defect Density = (Defect Count)/ (Size of module or software)

  • The defect density is counted per thousand lines of code and is called as KLOC.
  • The standard for defect density is not fixed. But, one defect per thousand lines of code is considered as good quality of the project.

 

Software Reliability : Defect Prevention

  • Defect Prevention is a plan made out to reduce the number of defects in a software product by identifying the cause of defect and preventing them to cause other problems in the software.
  • The strategy of defect prevention is to analyse the phases of the software product where the defects were arrived previously and preventing the occurrence of those defects in future.
  • Defect Prevention causes an increase in productivity and effort reduction.

 

Software Reliability : Defect Containment

  • It is a strategy, an attempt to increase the software quality and reducing the cost of the software product simultaneously.
  • Defect containment is reported usually as a percentage of defects captured in the phase in which they are originated.
  • Also, it is a process of displaying the information about the issues and problems occurred and reported for a software system.

 

Software Reliability : Inspection in Software Quality

  • Inspection in software project often leads to verification of quality of that software product.
  • With a goal of identifying the defects, Inspection refers to peers review of a software product done by individuals in order to look for defects using certain well defined processes.
  • The stages of inspection of software quality includes:
    1. Planning.
    2. Overview Meetings.
    3. Preparation.
    4. Inspection Meeting.
    5. Follow Up.
    6. Rework.