What does the test describe that involves examining a relationship between two things, called variables that make prediction about the way users will perform with an interface?

Hypotheses.

Explanation:

Hypotheses:-It is a theory that is temporarily accepted to interpret certain phenomena or event, and to provide direction for investigation yet to come. A hypothesis can be proved correct or wrong, and must be capable of dis confirmation. If it remains validated by facts, it is said to be corroborated.