Designing and developing new apps for your customers to use can be hugely advantageous to your organization. However, the quality of the apps you build will dictate how successful they become. If you design a mobile app for customers that’s broken, they won’t use it. Not only will your attempt to improve their experience be fruitless, but it could even have the reverse effect by harming your brand’s reputation. Even relatively minor issues can hamper the functionality of your app. Because of this, you’ll want to continually measure and monitor the quality of your software. This can be a bit overwhelming considering the vast number of software quality metrics available, but we’ve narrowed it down to 12 that you should focus on.
Define Software Quality Metrics
Before going into the 12 software quality metrics you should be monitoring throughout the development and deployment of your software applications, let’s delve deeper into what software quality metrics actually are and why they’re important.
At their core, software quality metrics allow you to identify whether your software is meeting its functional and nonfunctional requirements. More specifically, they provide quantifiable measurements of certain software characteristics. Monitoring these metrics allows you to measure the performance of your software, measure productivity, plan work items, and more.
Benefits of Monitoring Software Quality Metrics
There are three main reasons why you should monitor software quality metrics: to determine the quality of your current software (or software development process), to improve the quality of your software, and to predict the quality of the software once it’s launched. The information provided by software quality metrics will also result in several other benefits, including:
- The ability to prioritize issues, improve team productivity, and help to reduce overtime
- To better manage your software development workflow
- The ability to reduce overall costs by addressing potential issues before they become significant problems
- The ability to increase the overall ROI (return on investment) of your software development
Indicators of Software Quality
A number of factors will indicate the quality of your software. These software quality metrics you use should help you judge the following:
- Reliability – Reliability refers to how stable the app is and how it performs (as in, what it’s risk of failing is) under unexpected conditions. An application that is reliable should experience few errors and minimal downtime and should have good data integrity.
- Performance efficiency – Performance efficiency relates to a software’s use of resources as well as how that affects the satisfaction of the user, the response times, and the scalability of the software. Several factors contribute to the performance efficiency of an app, including individual architectural components, the source code design, and the architecture of the software.
- Security – The security of an application refers to how effectively it protects information against data breaches. The number of security vulnerabilities (as well as the severity of those vulnerabilities) indicate how secure an application is. One of the common causes of security vulnerabilities found in software is poor coding.
- Maintainability – The maintainability of an app refers to how easy it is to modify, adapt, or transfer. Maintainability depends heavily on consistent coding and compliance with the software’s architectural rules.
- Rate of delivery – The rate of delivery is the number of new versions of your software sent to your customers. These new versions are typically updates that improve the user experience, which means that a higher rate of delivery indicates better software quality.
- Testability – Your software should be easy to test. The easier it is to test, the easier it will be to find issues with the software and easier to ensure the quality of the apps that you deploy into production.
- Usability – The usability of your software refers to how effective the app’s user interface is. Usability is essential to ensuring that your users get the most out of your software. Factors like task execution speed and simplicity greatly affect the usability of an app.
The first four software quality metrics you should monitor are product metrics. Product metrics describe the characteristics of your app, including how your app performs, how complex it is, how large it is, what design features it has, and its quality level.
Product Quality Metrics
These are the four main product quality metrics you should monitor:
Mean Time To Failure
The mean time to failure is the amount of time that goes by between failures. The longer the mean time to failure is, the better. It’s a metric most commonly used for safety critical systems; for example, airline traffic control systems.
Defect density measures the amount of defects found in the software compared to the size of the software, allowing you to analyze the code quality per unit.
Customer problems is a pretty self-explanatory metric. It measures the number of problems that customers encounter when using your app. This includes both defect problems and non-defect problems (such as issues with the user interface). The customer problems metric is usually measured as the total number of user problems reported within a month. You should monitor the metric on a monthly basis following the release of your software.
Measuring how satisfied your customers are with the software is a good indication of its quality. However, obtaining the customer satisfaction measurements requires you to conduct surveys. Customer surveys can measure customer satisfaction either as a percent of satisfied customers or percent of non-satisfied customers.
Process metrics should be used to identify the quality of your software during the course of development.
In-Process Quality Metrics
Be sure to monitor the following four in-process quality metrics:
Defect Density During Machine Testing
Testing for defects during the development of your software will predict the defect rate of the software released on the market. If the defect density is high during testing, it means there was likely a high rate of errors occurring during the development of your app.
Defect Arrival Pattern During Machine Testing
Although monitoring the defect density during machine testing can give you an idea of how many defects are appearing in your software during its development, it’s only a summary of the defects. The defect arrival pattern will provide you with details about the different quality levels of the software in the field, including:
- The number of defects reported during the testing phase by time interval.
- The pattern of valid defects that are newly discovered once problem determination has been completed on reported problems. This indicates a real defect pattern.
- The pattern of defect backlog overtime (helpful since not all reported problems can be addressed right away). If the defect backlog is large, the overall quality of the software will be affected and retesting may be required.
Phase-Based Defect Removal Pattern
Monitoring the phase-based defect removal pattern allows you to track defects occurring throughout the development of your app. This includes not just the testing phase, but also the software’s design review, inspections of the software code, and the formal verifications done prior to testing. Software defects are often caused by design issues. Performing formal reviews will help remove defects at the front-end and minimize the errors in your software.
Defect Removal Effectiveness
Defect removal effectiveness (sometimes also referred to as defect removal efficiency) is calculated by dividing the number of defects removed during the software’s development phase by the defects that are latent in the final software product. This number should then be multiplied by 100 to determine the rate of defect removal. The higher the number is, the more effectively you were able to remove defects during the developmental process.
Project metrics measure the characteristics and execution of a software development project. This can include the cost of the project, the schedule of the project, the productivity of the project team, the staffing pattern over the course of the project, and the number of software developers dedicated to the project.
Maintenance Quality Metrics
Use the following software quality metrics to monitor your app’s maintenance quality and to potentially address issues following its release:
Fix Backlog And Backlog Management Index
The fix backlog and backlog management index metric refers to the rate of newly discovered defects and the rate at which fixes become available for problems that are reported. It refers to the number of reported problems remaining at the end of a specified period of time (such as at the end of each week or month). The BMI (backlog management index) is calculated by dividing the number of problems closed during the specified time period by the number of problems discovered during that same time period. Monitoring this metric can provide you with valuable information for managing your software’s maintenance process.
Fix Response Time And Fix Responsiveness
The Fix Response Time is typically the mean time of all problems from the time that they are reported to the time that they are fixed. The shorter the fix response time is, the more satisfied your customers will generally be. The effectiveness of your fix responsiveness depends heavily on the agreed-to fix time, your customer’s expectations, and the ability to meet your commitment to your customers.
Percent Delinquent Fixes
The percent delinquent fixes is a metric that’s calculated by dividing the number of fixes that exceeded your response time criteria by the number of fixes completed within a specified period of time.
The last metric is fix quality. Fix quality refers to the number of defective fixes. A fix is considered defective if it did not fix the initial defect — or if it did fix the initial defect but caused another one as a result. Defective fixes can be incredibly detrimental to the customer experience, especially in the cases of mission-critical software.
You can measure fix quality in two different ways — you can measure defective fixes by recording them in the month that the defective fix was discovered or in the month that the defective fix was delivered. When recording defective fixes in the month that they were discovered, it’s a customer measure. When recording defective fixes in the month that they were delivered, it’s a process measure. The difference between the date of the customer measure and the process measure is known as the latent period of the defective fix. The longer the latency, the worse your customer satisfaction will be.
Guidelines When Monitoring Metrics
Ensuring the quality of your software isn’t just about monitoring these 12 software quality metrics — it’s about using them effectively. Some guidelines to follow when using these 12 metrics will ensure that they provide you with actionable insight:
Establish Goals To Link Metrics To
By linking the metrics you’re monitoring to specific goals, it will be easier to set targets using those metrics to help your development team improve the usefulness of your software as well as overall user experience. Developers often use metrics to track their progress towards the goals you’ve established. For example, these goals could include reducing the number of reported bugs or reducing the lines of code in your software.
Analyze Trends Instead Of Numbers
Many of these software quality metrics will provide you with numbers that can tell you whether your team has met certain goals or not; however, they are more effective when you compare them over time. By comparing data points over time, you can identify positive and negative trends, which is far more helpful. Being able to analyze whether a metric is trending up or down can tell you much more about the process, whether you’re making progress, and whether any changes you’ve implemented are having the intended effect. Just because a number indicates that a goal hasn’t been met doesn’t mean that progress hasn’t been made, which is why analyzing the trend is so important.
Establish Shorter Measurement Periods
An argument can be made that you don’t want developers to constantly disrupt their progress by checking your metrics. However, you should think about establishing shorter measurement periods so that developers can check their progress regularly. Establishing shorter timeframes for your measurement periods will give your team more time to adjust their tactics if necessary. Shorter time frames will also result in more data points that can be used to track trends more effectively.
Use Metrics That Actually Lead To Change
While we highly recommend using the 12 metrics that we outlined, there may be other software quality metrics that are worth monitoring. However, be sure to analyze the metrics themselves once in a while to determine whether they are actually helping you. Some metrics do a poor job of indicating software quality or workflow quality. Test for whether the metrics you’re tracking are capable of measuring progress towards your goals. If they don’t, don’t use them — they are just a waste of your time.
Software Quality Matters
Designing and developing new software can greatly improve your customer experience; however, the ability to do this depends on the quality of the software. A poor quality app isn’t going to do much in the way of improving customer experience — instead, it will just hinder it. Monitoring the quality of your software is critical throughout the development stages as well as following its launch. The most effective way to do this is by monitoring 12 of the most important software quality metrics. To ensure that these metrics have the intended results, link your metrics to specific goals and be sure to track how your metrics are trending over time instead of just paying attention to individual numbers.
Do you need guidance in improving your software’s quality? Contact us for assistance.