Before beginning the test, individuals taking one of the Wechsler Intelligence Scales are informed that some questions will be easy, some questions will be difficult, and test takers are not expected...

Before beginning the test, individuals taking one of the Wechsler Intelligence Scales are informed that some questions will be easy, some questions will be difficult, and test takers are not expected to be able to answer every question. Why is this information a sign of a good test?