What are the best ways to increase the validity and reliability of usability testing?

1 Define clear objectives

Before conducting a usability test, you should have a clear idea of what you want to learn from it. What are the main questions you want to answer? What are the success criteria and metrics you want to use? How will you analyze and interpret the data? Having clear objectives will help you design a test that is relevant, focused, and aligned with your goals.

2 Choose appropriate methods

There are different types of usability testing methods, such as lab testing, field testing, remote testing, moderated testing, or unmod moderated testing. Each method has its own advantages and disadvantages, depending on the context, resources, and objectives of the test. You should choose a method that suits your needs and allows you to collect valid and reliable data. For example, if you want to test a product in a realistic environment, you may opt for field testing. If you want to test a product with a large and diverse sample, you may opt for remote testing.

3 Recruit representative users

The users who participate in your usability test should represent your target audience as much as possible. This means that they should have similar characteristics, needs, preferences, and behaviors as your intended users. Recruiting representative users will help you increase the external validity of your test, meaning that the results can be generalized to other users in similar situations. You should also recruit enough users to ensure that your results are statistically significant and not influenced by outliers or random errors.

4 Prepare realistic tasks and scenarios

The tasks and scenarios that you ask your users to perform during the test should reflect the real-world use cases of your product, system, or service. They should be relevant, meaningful, and challenging enough to elicit the user's natural behavior and feedback. Preparing realistic tasks and scenarios will help you increase the ecological validity of your test, meaning that the results can be applied to other settings and conditions.

5 Control confounding variables

Confounding variables are factors that can affect the outcome of your test, but are not related to your objectives or hypotheses. They can introduce noise, bias, or error into your data and reduce the internal validity of your test, meaning that the results may not reflect the true relationship between the independent and dependent variables. You should try to control confounding variables as much as possible by standardizing the test environment, instructions, procedures, and tools. You should also monitor and document any potential confounding variables that may occur during the test.

6 Evaluate and improve your test

After conducting a usability test, you should evaluate how well it met your objectives and followed your methods. You should also assess the quality of your data and identify any limitations, challenges, or issues that may have affected the validity and reliability of your test. You should use this evaluation to improve your test design, execution, and analysis for future iterations. You should also communicate your findings and recommendations clearly and transparently to your stakeholders and users.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?