How is usability testing different from interviews or focus groups?
Focus groups and interviews are mostly about gathering opinions, ideas and thoughts. In focus groups, you show participants a product, or describe the product. Then you ask them what they think of the product, the features, the design, etc.
In usability testing, we get the user to use the product and observe how they use it, identify problems users encounter while using the product, etc. While the user is playing around with your product, we ask them to “think aloud” so that we can understand how they are interacting with your product. The hands-on interaction with your product is what distinguishes usability testing from pure interviews or focus groups.
That doesn’t mean that we don’t bother to ask users for their opinion. Most of the time, there is a pre-test questionnaire and a post-test questionnaire to gather opinions or gauge “subjective satisfaction”.