What are the Metrics Needed for Effective Mobile App Testing?
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Today’s world is mobile-first. With the smartphone revolution, users expect most applications to work seamlessly on mobile devices and to be fast, stable, secure, and intuitive. With millions of apps available across app stores, even a single negative experience, such as a crash, slow load time, or mishandled workflow, may lead to poor ratings for the app. This is where mobile app testing and the metrics that measure the various app parameters become mission-critical.
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This article examines the key metrics required for effective mobile app testing, including their categories, descriptions, importance, and how teams can utilize them to deliver high-quality mobile apps consistently.
What are Mobile App Testing Metrics?
Mobile app metrics are a quantifiable measure of a mobile app’s performance across various aspects of the user journey.
Mobile app metrics reveal how well your app is performing and identify areas for improvement. These metrics keep users informed about user retention, engagement, and revenue-generating potential.
If a mobile app advertisement campaign increases app downloads but the retention rate is low, it can be concluded that there is an issue with user experience or value delivery. If a significant number of users utilize the app but revenue is low, you may need to refine your marketing and monetization strategies to increase revenue.
In this way, tracking mobile app metrics provides actionable insights to help you improve your strategies and the app itself.
For more details on QA Metrics, read the article, QA Testing KPIs: Driving Success Through Measurable Metrics.
How to Choose the Right Mobile App Metrics to Track
There are dozens of app metrics available today, and it is essential to choose those that align with your business requirements and the type of app you are developing.
In general, consider the following when choosing the app testing metrics:
- Determine the Term “Success” For Your App: When will you say your app is successful? Is it when it has high user retention and millions of downloads? Frequent in-app purchases, or strong viral growth?
- Identify Your North Star Metric for the App: The North Star metric is the single KPI that best reflects the core value of the application. Choose a mobile app metrics that drive or impact the North Star metric.
- Establish Benchmarks for Each Metric: Use historical data or industry standards to set realistic benchmarks for each metric you choose for your mobile app.
- Prioritize Actionable Metrics: Do not focus on vanity metrics unless they provide actionable insights.
Mobile App Testing Metric Classification
Mobile app testing metrics can be broadly categorized into:
- User Acquisition & Activation Metrics
- User Engagement Metrics
- User Retention Metrics
- Monetization & Revenue Metrics
- User Experience & Performance Metrics
- Marketing & Acquisition Cost Metrics
- User Satisfaction & Feedback Metrics
- Compatibility Metrics
- Security Testing Metrics
The detailed classification is shown in the figure below:
In the following sections, we will cover the various mobile app testing metrics that are commonly used.
User Acquisition & Activation Metrics
These metrics measure how well your app is attracting new users and how many are signing up. The values returned by these metrics directly coincide with your marketing campaigns and the effectiveness of your onboarding process. Here are the main metrics under this category:
App Downloads
This metric returns the number of times your app is downloaded and installed by users. App downloads are a basic measure of your app’s initial popularity and the effectiveness of your marketing efforts.
As app downloads mark the first step in user acquisition, spikes in downloads indicate successful campaigns or the release of attractive features.
The value returned by this metric is simply the count of app installations.
User Growth Rate
User Growth Rate = (Current period users - Previous period users) / Previous period users x 100%
A higher growth rate indicates healthy growth of the app, driven by successful user acquisition strategies and increasing popularity.
A slower growth rate, on the other hand, indicates that you need to invest more in acquisition strategies.
Install Trend
This metric provides the pattern of mobile app installs over a given period of time. The pattern may be a trajectory of daily or weekly download counts.
The install trend metric provides the context beyond the number of downloads. It indicates a trend in app installation. Whereas a rising trend indicates positive momentum and effective marketing, a downward trend indicates increased competition or a saturated interest.
Registrations (Sign-Ups)
App registration is the process of creating an account or signing up for the app. The registration rate is the percentage of app downloads that are converted into registered users.
Registration Rate = (Number of registrations / Number of installs) x 100%
The higher the registration rate, the effective your onboarding process. A lower conversion from install to sign-up means either your sign-up process is too lengthy, requires too much data for registration, or that users are not interested in the app.
Activation Rate
An ‘activation’ for an app is the initial action that is performed on the app once registration is complete. Activation rate refers to the percentage of users who complete the activation process for your app. The activation step may be clicking on the link sent in an email, completing a tutorial, making the first transaction, or simply launching the app for the second time.
Activation Rate = (Number of new users who reach the activation event / Number of new users) x 100%
A high activation rate implies higher user retention, while a low activation rate signals that users are not finding value quickly or dropping off for various reasons.
User Engagement Metrics
These metrics indicate how actively and frequently users interact with your app. Some of the metrics used are:
Daily Active Users (DAU)
DAU refers to the number of unique active users who open or interact with your app daily. The term “Active user” means the user has launched the app or taken a specific action. Generally, DAU refers to anyone who has had at least one session with the app within 24 hours.
DAU indicates the size of the highly engaged user base, with a higher value suggesting increasing daily utility; a shrinking DAU indicates that users are losing interest or churning.
Monthly Active Users (MAU)
MAU is the number of unique users who engage with the app in a 30-day (monthly) period. This metric has a broader net than DAU and captures infrequent users as well. MAU is the effective metric for apps that are not used daily, for example, ticket booking apps.
A higher MAU indicates that the app is attracting more users each month.
Sessions
A session is a period encompassing one continuous use of the app by a user, from login to exit (i.e., from opening the app to closing it).
Average Sessions per User = Total sessions in period / Total active users in period
The number of sessions per user measures how actively the user uses the app. A higher number of sessions indicates frequent user engagement, while a lower number signals an unpopular app.
By tracking app sessions, you can understand usage patterns and adjust or refine your strategies accordingly.
Session Length (Average Session Duration)
The length of a session refers to the average amount of time a user spends in the app during a single session. For apps like utilities, a shorter session indicates efficiency, while for video streaming apps, a longer session may be more helpful.
Average Session Length = Total duration of all sessions / Number of sessions (in a given period)
Session Interval
Average Session Interval = Total time between subsequent sessions for all users/number of intervals
The session interval metric shows how frequently users return to the app. A shorter session interval indicates that users habitually check the app, which is better for engagement. However, some apps with higher user engagement, such as airline booking apps, may have longer session intervals.
Bounce Rate
This refers to the percentage of users who open the app and then leave after a brief interaction (typically defined as viewing only one screen or failing to perform any meaningful action).
Bounce Rate = (Number of single-page sessions / Total number of sessions) x 100%
A high bounce rate indicates that users are either unable to find what they want or encounter difficulties in doing so.
Acquisition efforts will be wasted if the app continues to have a high bounce rate. Hence, it is critical to reduce the bounce rate.
Error Rate
The error rate for an app is the number of user errors encountered during each task execution. A higher error rate indicates poor UI design, confusing navigation, and inadequate feedback messages.
Teams should strive to reduce the error rate by providing user-friendly UI, flexible navigation, and clear messages.
User Satisfaction Score
This is a qualitative measure, gathered through ratings, feedback, or surveys. User feedback and experience are gathered through in-app surveys, app store reviews, and Net Promoter Score (NPS).
User Retention Metrics
User retention measures the app’s ability to attract and retain users over time. Retention indicates loyalty and the long-term stickiness to the app. The metrics that come under user retention are:
Retention Rate
Retention Rate = (Users active at time X who were also active at the start / Users active at start) x 100%
This is a key metric for mobile apps as it signifies user satisfaction and app value. A high retention rate indicates that the app is enjoyable enough for users to continue using it over time. A low retention rate signals issues with user experience, a lack of proper content, or a mismatch of expectations, as users try the app and then abandon it.
Churn Rate
Churn Rate = (Number of users who left in period / Number of users at start of period) x 100%
If churn rate is higher than acquisition rate, it indicates a shrinking of the user base. It is a red flag that signals the app is driving away users, and you should take adequate steps to lower the churn rate.
Uninstall Rate
The percentage of users who uninstall the app from their device is known as the uninstall rate and represents a specific form of churn.
Uninstall Rate = (Number of uninstalls / Number of installs) x 100% over a period
A higher uninstall rate is more severe than the churn rate, as it indicates that users have decided not to return to the app in the near future. Higher uninstall rates indicate poor experience or unmet expectations.
Monetization & Revenue Metrics
These metrics measure how your app generates revenue and the financial value of your users. Some of the metrics in this category are:
Average Revenue Per User (ARPU)
ARPU = Total Revenue in period / Total Users in period
ARPU provides a quick snapshot of the revenue health of the mobile app. A rising ARPU means better monetization. It is often used for comparing the monetization efficiency before and after changes to the app.
Average Revenue Per Paying User (ARPPU)
ARPPU refers to the average revenue per paying subscriber (a user who has made a purchase) over a specified period. ARPPU focuses solely on users who generate revenue, excluding non-paying users from the metric.
ARPPU = Total Revenue from paying users / Number of paying users
Although an app may have a small number of paying users, if ARPPU is high, then those few are generating a significant amount of revenue.
Customer Lifetime Value (CLV)
CLV = Average Purchase Value x Average Purchase Frequency x Average Customer Lifespan
A set of users with a high average CLV is valuable to the app.
Conversion Rate
This indicates the percentage of users who complete a desired goal out of those who could. There are several conversion rates in an app, including install-to-registration conversion, trial-to-subscriber conversion, and add-to-cart-to-purchase conversion. A typical conversion rate that is often considered is the user transitioning from free access to a paid subscription.
Conversion Rate = (Number of users who completed the goal / Number of users who were eligible for the process) x 100%
The conversion rate metric is the core mobile app success metric for revenue.
User Experience & Performance Metrics
An app must deliver a positive user experience (UX) to retain users and encourage engagement. App performance is crucial, particularly given the varying network conditions and hardware limitations. Here are the user experience and performance metrics required for effective mobile app testing:
Load Time
This refers to the time it takes for a mobile app to become usable upon launch or for a specific screen to load within the app.
A longer load time (more than 3 seconds) can lead to higher abandonment rates and also set the first impression. An app loading quickly (less than 3 seconds) feels more polished and trustworthy.
Crash Rate
Crash Rate = (Number of crashes / Number of sessions) x 100% (or per user)
Crashes can be simply counted daily or tracked per 1000 sessions. Frequent crashes (crash rate > 1%) quickly drive users away, hurting retention, satisfaction, trust, and app store ratings.
API Latency
Average API latency = total time of all API responses/number of calls.
Average API latency is measured especially for API calls that affect the user experience, such as fetching feed data or submitting a form.
A high value of API latency can make the app feel slow, leading to user frustration or drop-off. Latency should be monitored to spot server issues and improve performance, ensuring smoother, faster user experiences.
App Stability Rate
App stability rate is an overall measure of stability and is often expressed as the percentage of sessions without crashes or errors. This metric is used as a high-level KPI for technical quality.
Crash-Free Sessions% = (Sessions without a crash / Total sessions) x 100%
A higher stability rate (close to 100%) indicates a smooth user experience, and a drop in the stability rate is a significant concern.
Response Time
The response time metric measures the time it takes for the app to respond to user actions, such as tapping a button or loading a screen. The response time metric is particularly significant in critical scenarios, such as login, search, checkout, and API responses.
Resource Utilization
This metric measures the usage of various app resources, including CPU, memory, battery, and network. This is important because it affects user engagement and retention.
For example, an app that drains the battery or consumes excessive memory will be uninstalled by the user.
Learn more about performance testing in this article.
Marketing & Acquisition Cost Metrics
These metrics focus on user acquisition and the associated costs incurred. For app marketers, these measures are crucial for measuring campaign ROI and optimizing the marketing channel mix. Metrics that come under this category are:
Customer Acquisition Cost (CAC)
This metric defines the average cost to acquire a user and is calculated by dividing total marketing spend by the number of new users. CAC can be tracked as an overall app value or by channel.
CAC = Total marketing cost / Number of new users acquired
It is a key for budgeting and rising CAC signals, ad fatigue, or poor targeting.
Cost Per Install (CPI)
CPI = Ad Spend / Number of installs from that ad campaign.
It is widely used in mobile marketing. A low CPI is usually good, but may also indicate cheap installs that may not retain.
Cost Per Acquisition (CPA)
CPA is the cost incurred per conversion (such as installs to sign-ups or add-to-cart to purchases).
CPA = Ad Spend / Number of conversions (of the defined event)
CPA better aligns with business goals and focuses on the deeper funnel.
Return on Investment (ROI)
ROI is the measure of net profit from a campaign divided by its cost. ROI helps identify the profitable channels and shows if campaigns are truly paying off.
ROI = (Gain from Investment - Cost of Investment) / Cost of Investment x 100%
Click-Through Rate (CTR)
CTR = (Number of clicks / Number of impressions) x 100%
CTR shows the popularity of your ad, and a high CTR often means more installs.
Cost Per Click (CPC)
CPC = Total ad spend / Number of clicks
As many ad platforms charge per click, this represents the spend divided by the number of clicks.
CPC, together with the conversion rate, determines acquisition cost. A high CPC is only worth it if conversion or CLV is strong.
Virality (K-Factor)
K = Average number of invitations sent by each user x Conversion rate of those invitations
Virality turns users into app promoters and drives low-cost growth.
User Satisfaction & Feedback Metrics
These are qualitative measures that gauge the sentiment of your users that are beyond what you see in usage numbers. These measures are often collected from surveys or feedback tools.
You can better understand the overall customer sentiment and loyalty by tracking these metrics. Popular user satisfaction and feedback metrics are:
Net Promoter Score (NPS)
NPS = % Promoters - % Detractors
NPS is an indicator of loyalty and overall satisfaction that users have for the app. A high NPS indicates users love your app enough to promote it. A low or negative NPS is a warning that users are unhappy and they will not endorse it even if they are using it.
Customer Satisfaction Score (CSAT)
The measure of users’ satisfaction with the app, typically collected through simple survey questions such as “How do you rate the app?” or “How would you rate the overall satisfaction with the app?” is the CSAT. It is usually measured on a scale of either 1 to 5 stars or a numeric range from 1 to 10.
CSAT is seen as a quick pulse on user happiness at specific moments. It can also be measured for specific features or changes. High CSAT indicates the app meets or exceeds user expectations, while a low CSAT signals that the users are displeased with the app.
Compatibility Metrics
These metrics provide a measure of app compatibility with the operating system (OS) or network. The related metrics are:
OS Compatibility Rate
This is the percentage of supported OS versions on which the app functions correctly. Sometimes users may delay OS updates, making backward compatibility necessary.
Network Compatibility
The network compatibility metric measures the app performance across various network conditions, such as 2G, 3G, 4G, 5G, WiFi, online/offline mode, and network switching.
Security Testing Metrics
Security is paramount to apps, especially for those handling personal or financial data. Security testing metrics measure how secure the app is and how it handles security-related issues. Security testing is covered in this article.
The following security testing metrics are used for effective testing:
Vulnerability Count
This metric provides the number of security vulnerabilities identified during testing. Some of these vulnerabilities are insecure data storage, weak authentication, or improper session handling.
Security Test Coverage
The extent to which security requirements are verified and covered in the app determines the security test coverage. This metric ensures compliance with standards such as OWASP Mobile Top 10.
Conclusion
Mobile app testing is effective not when you find too many bugs, but when you also measure quality in a structured, repeatable, and meaningful way. Metrics help you determine application stability, performance, usability, security, and the efficiency of the testing process itself.
By tracking the right combination of parameters during testing, teams can make informed release decisions, improve user satisfaction and experience, reduce production issues, and optimize testing efforts.
Using these metrics, mobile app testing is transformed from a subjective activity into a strategic, data-driven discipline that delivers successful mobile applications in today’s competitive landscape.
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