GuidesUser experience (UX)7 usability metrics you should be tracking

7 usability metrics you should be tracking

Last updated

19 November 2023

Author

Dovetail Editorial Team

Let's talk about metrics. You can't conduct business, leverage tools, or effectively research without them. There isn't an aspect of your company or organization that doesn't heavily rely on data.

But metrics can be nuanced beyond basic calculations. More specifically, usability metrics can bring more insights and knowledge to every process you use and decision you make.

Usability metrics are unique since they're used to quantify how "usable" something is in achieving a goal. This article explores usability metrics, what they are, and how you can tap into them for precise results. Discover how useful usability metrics are for improving your processes, research, and business objectives.

What are usability metrics?

Usability is generally measured by a number of observable and quantifiable metrics, for example:

  • How satisfied users are

  • How quickly they complete a task

  • How many errors they make when interacting with a digital product

These metrics provide valuable insights into the user experience, allowing for data-driven decision-making and iterative improvements to enhance the overall usability of a unique product.  

Why would you need to measure usability?

There are inherent benefits to leveraging usability metrics and countless reasons to include them as part of your continuing evaluations. After all, you don't want your teams wasting time and resources on unjustified priorities.

Let’s look at just a few of the key advantages of tapping into usability metrics.

  • Benchmarking: Usability measures provide baseline data to compare different design iterations or products, even competitors, allowing for continuous improvement

  • Data-driven decisions: They enable data-driven decision-making, reducing reliance on subjective opinions or assumptions

  • Issue prioritization: They help the product team prioritize usability issues based on their severity and impact on user interactions

  • Communication: Usability metrics allow for more thorough communication about the particular system or solution you're using

  • Usability compliance: Usability metrics help ensure compliance with usability standards and guidelines, which may be required in some industries

What are the best metrics to measure?

Usability metrics are designed to define the "extent to which a product can be used" and achieve specific objectives, as ISO 9241-11 describes. The most common metrics to measure include those points usually associated with something being deemed "usable."

Usability metrics and the testing methods for gathering these usability insights primarily shed light on effectiveness, efficiency, and satisfaction.

Effectiveness

This usability dimension refers to the ability of the users to accomplish their goals accurately when interacting with a product or system. It measures how well the product enables users to complete tasks and achieve their desired goals without any obstacles.

Efficiency

You'll also employ usability metrics to determine how many resources are used to get your product or process to work properly. More specifically, learn what it takes to accurately and completely accomplish your goal. You can then decide if the trade-off of resources for usability and outcomes makes sense for your situation.

From the user’s perspective, efficiency is pivotal since it refers to the resourcefulness and speed with which they can accomplish tasks when interacting with your system or product.

Satisfaction

Usability metrics can also help you evaluate how comfortable, acceptable, and easy your specified product or process is to use. From start to finish, learn how "satisfied" users are with using the specified method to achieve a goal.

Usability testing will ensure you routinely keep great methods over complicated or challenging methods to streamline how your teams complete tasks and accomplish goals.

7 important usability metrics and how to use them effectively

Now that you have a better understanding of what usability metrics are and what they measure, let's dive into how to use them. Whether you're looking for business applications or research-related effectiveness, these seven usability metrics tend to be the most important to leverage.

1. Task Success Rate

If you're using a tool or product that doesn't get the job done, it's not worth using. So, the most important usability metric to track is task success or completion rates.

Here's the calculation you'll use to determine the completion rate:

Task success rate = (number of tasks successfully completed / number of tasks undertaken) x 100%

2. Time on task

Next up in evaluating your product, tool, or process is the time spent on a task. How long it takes to use it, from start to successful finish, will help you determine whether or not it's worth using.

Sometimes, design, copy, software architecture, or instructions make a solution harder to use, thus taking longer than expected to achieve a goal.

Here's the calculation to determine a time-on-task rate:

Task time = End time – start time

3. Number of errors

Usability metrics can also calculate the number of errors that occur for the duration of the task. Errors can be user mistakes, unintentional actions, or omissions. So, review the number of errors through a lens of error severity.

Measuring your errors and assigning severity ratings can take more time than other usability metrics, but they're great for evaluating diagnostic data. And the higher the error rate, which you tally directly, the harder the product is to use.

4. Single Ease Question (SEQ)

Every person using your specified product or process should be provided with a questionnaire measuring the ease or difficulty of the task.

The Single Ease Question asks just one question about ease of use. It's the most popular post-task-related questionnaire and usually asks users to rate their experience on a seven-point scale.

5. Subjective Mental Effort Question (SMEQ)

In tandem with the SEQ, the Subjective Mental Effort Question questionnaire will link up to five questions to the assigned user in a post-task evaluation. It also measures how much mental effort goes into completing a specific task.

Again, these metrics prompt users to use a sliding number scale to rate how difficult they found the task to complete. These options include selections like “tremendously hard” and “not at all hard.”

6. Software Usability Measurement Inventory (SUMI)

If you're looking to evaluate your product on a mass scale and have a substantial budget to carry out a usability test across a broad group of users, you can use the SUMI method. This more comprehensive test usually incorporates 50 questions and assesses user sentiments about a process or product in a more in-depth manner.

It’s great for quickly assessing a product’s usability and combines data that evaluates the number of errors, task completion rates, task time, and overall satisfaction in one easy-to-apply metric.

7. Confidence

Customers who know they are using your products correctly are typically more confident that they are getting the right results. Not all products are so easy to use that users are certain they are doing so in the way your company intends. This uncertainty can cause them to question whether the results they are getting are correct.

We use a seven-point rating scale from “not confident at all” to “ extremely confident” to assess how confident users were that they completed a particular task successfully.

Usability success rates to consider

Usability metrics and testing don't have to result in 100% for your product to be effective or useful. In fact, the average usability scoring range falls around 78%.

Remember there will almost always be anomalies and outliers in your data. Any score over 75% is usually considered a good usability rating.

Summary

Measuring usability is essential for creating user-centered, effective, and competitive digital products while minimizing costs and maximizing user satisfaction.

FAQs

What are the most common usability metrics?

The most helpful usability metrics will depend on the nature of your business, but many of the most common metrics can be applied to nearly any business.

Some of the most common user metrics include: 

  • Task success rate: The percentage of users who successfully complete a specific task or set of tasks using the product

  • Time on task: The average amount of time users take to complete a task, indicating task efficiency

  • Error rate: The frequency at which users make errors while interacting with the product

  • Satisfaction scores: Users' self-reported satisfaction with the product, often measured using standardized surveys like the System Usability Scale (SUS) or (NPS)

What are metrics for user value?

Usability metrics can improve user value in several ways by providing quantifiable insights into the . When a company tracks task completion, error rates, or user satisfaction, for example, the product team can identify areas for improvement.

This will enable the entire team to enhance the usability of their product or interaction system, resulting in improved user value through increased efficiency, effectiveness, and overall satisfaction.

How many users should there be for a usability test?

According to Jakob Nielsen, a renowned UX industry leader, testing with five people is the sweet spot. However, the number of participants in qualitative research is often determined by the point at which saturation is reached. This occurs when interviewing more participants will not provide new information.

What are the four types of usability test questions?

There are four core types of usability test questions to consider adding to all your post-task screening initiatives:

  • Screening questions: Assess task expectations prior to use

  • Pre-task questions: Assess task introduction sentiments

  • In-task questions: Assess sentiments mid-task

  • Post-task questions: Assess overall ease or difficulty after the task is completed

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